diff --git a/core/src/main/java/google/registry/flows/FlowModule.java b/core/src/main/java/google/registry/flows/FlowModule.java
index bbabbfb80..aae0a55e0 100644
--- a/core/src/main/java/google/registry/flows/FlowModule.java
+++ b/core/src/main/java/google/registry/flows/FlowModule.java
@@ -15,6 +15,7 @@
 package google.registry.flows;
 
 import static com.google.common.base.Preconditions.checkState;
+import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.base.Strings;
 import dagger.Module;
@@ -222,6 +223,7 @@ public class FlowModule {
           String clientId,
           EppInput eppInput) {
     builder
+        .setModificationTime(tm().getTransactionTime())
         .setTrid(trid)
         .setXmlBytes(inputXmlBytes)
         .setBySuperuser(isSuperuser)
diff --git a/core/src/main/java/google/registry/flows/contact/ContactCreateFlow.java b/core/src/main/java/google/registry/flows/contact/ContactCreateFlow.java
index aa270bbcb..10d13a4c4 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactCreateFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactCreateFlow.java
@@ -93,7 +93,6 @@ public final class ContactCreateFlow implements TransactionalFlow {
     validateContactAgainstPolicy(newContact);
     historyBuilder
         .setType(HistoryEntry.Type.CONTACT_CREATE)
-        .setModificationTime(now)
         .setXmlBytes(null) // We don't want to store contact details in the history entry.
         .setContact(newContact);
     tm().insertAll(
diff --git a/core/src/main/java/google/registry/flows/contact/ContactDeleteFlow.java b/core/src/main/java/google/registry/flows/contact/ContactDeleteFlow.java
index 83170854b..c0764e576 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactDeleteFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactDeleteFlow.java
@@ -122,11 +122,7 @@ public final class ContactDeleteFlow implements TransactionalFlow {
       resultCode = SUCCESS;
     }
     ContactHistory contactHistory =
-        historyBuilder
-            .setType(historyEntryType)
-            .setModificationTime(now)
-            .setContact(newContact)
-            .build();
+        historyBuilder.setType(historyEntryType).setContact(newContact).build();
     if (!tm().isOfy()) {
       handlePendingTransferOnDelete(existingContact, newContact, now, contactHistory);
     }
diff --git a/core/src/main/java/google/registry/flows/contact/ContactTransferApproveFlow.java b/core/src/main/java/google/registry/flows/contact/ContactTransferApproveFlow.java
index 3e7fd21fc..437c23ac8 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactTransferApproveFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactTransferApproveFlow.java
@@ -22,6 +22,7 @@ import static google.registry.flows.ResourceFlowUtils.verifyResourceOwnership;
 import static google.registry.flows.contact.ContactFlowUtils.createGainingTransferPollMessage;
 import static google.registry.flows.contact.ContactFlowUtils.createTransferResponse;
 import static google.registry.model.ResourceTransferUtils.approvePendingTransfer;
+import static google.registry.model.reporting.HistoryEntry.Type.CONTACT_TRANSFER_APPROVE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableSet;
@@ -39,7 +40,6 @@ import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.poll.PollMessage;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
@@ -88,11 +88,7 @@ public final class ContactTransferApproveFlow implements TransactionalFlow {
     ContactResource newContact =
         approvePendingTransfer(existingContact, TransferStatus.CLIENT_APPROVED, now);
     ContactHistory contactHistory =
-        historyBuilder
-            .setType(HistoryEntry.Type.CONTACT_TRANSFER_APPROVE)
-            .setModificationTime(now)
-            .setContact(newContact)
-            .build();
+        historyBuilder.setType(CONTACT_TRANSFER_APPROVE).setContact(newContact).build();
     // Create a poll message for the gaining client.
     PollMessage gainingPollMessage =
         createGainingTransferPollMessage(
diff --git a/core/src/main/java/google/registry/flows/contact/ContactTransferCancelFlow.java b/core/src/main/java/google/registry/flows/contact/ContactTransferCancelFlow.java
index b1424c82f..c6ceb6049 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactTransferCancelFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactTransferCancelFlow.java
@@ -22,6 +22,7 @@ import static google.registry.flows.ResourceFlowUtils.verifyTransferInitiator;
 import static google.registry.flows.contact.ContactFlowUtils.createLosingTransferPollMessage;
 import static google.registry.flows.contact.ContactFlowUtils.createTransferResponse;
 import static google.registry.model.ResourceTransferUtils.denyPendingTransfer;
+import static google.registry.model.reporting.HistoryEntry.Type.CONTACT_TRANSFER_CANCEL;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableSet;
@@ -39,7 +40,6 @@ import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.poll.PollMessage;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
@@ -84,11 +84,7 @@ public final class ContactTransferCancelFlow implements TransactionalFlow {
     ContactResource newContact =
         denyPendingTransfer(existingContact, TransferStatus.CLIENT_CANCELLED, now, clientId);
     ContactHistory contactHistory =
-        historyBuilder
-            .setType(HistoryEntry.Type.CONTACT_TRANSFER_CANCEL)
-            .setModificationTime(now)
-            .setContact(newContact)
-            .build();
+        historyBuilder.setType(CONTACT_TRANSFER_CANCEL).setContact(newContact).build();
     // Create a poll message for the losing client.
     PollMessage losingPollMessage =
         createLosingTransferPollMessage(
diff --git a/core/src/main/java/google/registry/flows/contact/ContactTransferRejectFlow.java b/core/src/main/java/google/registry/flows/contact/ContactTransferRejectFlow.java
index 34bb7c1c2..6789e791f 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactTransferRejectFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactTransferRejectFlow.java
@@ -22,6 +22,7 @@ import static google.registry.flows.ResourceFlowUtils.verifyResourceOwnership;
 import static google.registry.flows.contact.ContactFlowUtils.createGainingTransferPollMessage;
 import static google.registry.flows.contact.ContactFlowUtils.createTransferResponse;
 import static google.registry.model.ResourceTransferUtils.denyPendingTransfer;
+import static google.registry.model.reporting.HistoryEntry.Type.CONTACT_TRANSFER_REJECT;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableSet;
@@ -38,7 +39,6 @@ import google.registry.model.domain.metadata.MetadataExtension;
 import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.poll.PollMessage;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
@@ -82,11 +82,7 @@ public final class ContactTransferRejectFlow implements TransactionalFlow {
     ContactResource newContact =
         denyPendingTransfer(existingContact, TransferStatus.CLIENT_REJECTED, now, clientId);
     ContactHistory contactHistory =
-        historyBuilder
-            .setType(HistoryEntry.Type.CONTACT_TRANSFER_REJECT)
-            .setModificationTime(now)
-            .setContact(newContact)
-            .build();
+        historyBuilder.setType(CONTACT_TRANSFER_REJECT).setContact(newContact).build();
     PollMessage gainingPollMessage =
         createGainingTransferPollMessage(
             targetId, newContact.getTransferData(), now, Key.create(contactHistory));
diff --git a/core/src/main/java/google/registry/flows/contact/ContactTransferRequestFlow.java b/core/src/main/java/google/registry/flows/contact/ContactTransferRequestFlow.java
index 473927ac0..29b075849 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactTransferRequestFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactTransferRequestFlow.java
@@ -24,6 +24,7 @@ import static google.registry.flows.contact.ContactFlowUtils.createGainingTransf
 import static google.registry.flows.contact.ContactFlowUtils.createLosingTransferPollMessage;
 import static google.registry.flows.contact.ContactFlowUtils.createTransferResponse;
 import static google.registry.model.eppoutput.Result.Code.SUCCESS_WITH_ACTION_PENDING;
+import static google.registry.model.reporting.HistoryEntry.Type.CONTACT_TRANSFER_REQUEST;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableSet;
@@ -45,7 +46,6 @@ import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.eppcommon.Trid;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.poll.PollMessage;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.ContactTransferData;
 import google.registry.model.transfer.TransferStatus;
@@ -120,10 +120,7 @@ public final class ContactTransferRequestFlow implements TransactionalFlow {
             .setTransferStatus(TransferStatus.SERVER_APPROVED)
             .build();
     Key<ContactHistory> contactHistoryKey = createHistoryKey(existingContact, ContactHistory.class);
-    historyBuilder
-        .setId(contactHistoryKey.getId())
-        .setType(HistoryEntry.Type.CONTACT_TRANSFER_REQUEST)
-        .setModificationTime(now);
+    historyBuilder.setId(contactHistoryKey.getId()).setType(CONTACT_TRANSFER_REQUEST);
     // If the transfer is server approved, this message will be sent to the losing registrar. */
     PollMessage serverApproveLosingPollMessage =
         createLosingTransferPollMessage(targetId, serverApproveTransferData, contactHistoryKey);
diff --git a/core/src/main/java/google/registry/flows/contact/ContactUpdateFlow.java b/core/src/main/java/google/registry/flows/contact/ContactUpdateFlow.java
index e8128c17f..bfca805d6 100644
--- a/core/src/main/java/google/registry/flows/contact/ContactUpdateFlow.java
+++ b/core/src/main/java/google/registry/flows/contact/ContactUpdateFlow.java
@@ -24,6 +24,7 @@ import static google.registry.flows.ResourceFlowUtils.verifyOptionalAuthInfo;
 import static google.registry.flows.ResourceFlowUtils.verifyResourceOwnership;
 import static google.registry.flows.contact.ContactFlowUtils.validateAsciiPostalInfo;
 import static google.registry.flows.contact.ContactFlowUtils.validateContactAgainstPolicy;
+import static google.registry.model.reporting.HistoryEntry.Type.CONTACT_UPDATE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableSet;
@@ -45,7 +46,6 @@ import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.EppResponse;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import java.util.Optional;
 import javax.annotation.Nullable;
@@ -146,8 +146,7 @@ public final class ContactUpdateFlow implements TransactionalFlow {
     validateAsciiPostalInfo(newContact.getInternationalizedPostalInfo());
     validateContactAgainstPolicy(newContact);
     historyBuilder
-        .setType(HistoryEntry.Type.CONTACT_UPDATE)
-        .setModificationTime(now)
+        .setType(CONTACT_UPDATE)
         .setXmlBytes(null) // We don't want to store contact details in the history entry.
         .setContact(newContact);
     tm().insert(historyBuilder.build());
diff --git a/core/src/main/java/google/registry/flows/domain/DomainCreateFlow.java b/core/src/main/java/google/registry/flows/domain/DomainCreateFlow.java
index c450504c9..0c7221702 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainCreateFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainCreateFlow.java
@@ -48,6 +48,7 @@ import static google.registry.model.registry.Registry.TldState.GENERAL_AVAILABIL
 import static google.registry.model.registry.Registry.TldState.QUIET_PERIOD;
 import static google.registry.model.registry.Registry.TldState.START_DATE_SUNRISE;
 import static google.registry.model.registry.label.ReservationType.NAME_COLLISION;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_CREATE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
 import static google.registry.util.DateTimeUtils.leapSafeAddYears;
@@ -495,12 +496,7 @@ public class DomainCreateFlow implements TransactionalFlow {
                       TransactionReportField.netAddsFieldFromYears(period.getValue()),
                       1)));
     }
-    return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_CREATE)
-        .setPeriod(period)
-        .setModificationTime(now)
-        .setDomain(domain)
-        .build();
+    return historyBuilder.setType(DOMAIN_CREATE).setPeriod(period).setDomain(domain).build();
   }
 
   private BillingEvent.OneTime createOneTimeBillingEvent(
diff --git a/core/src/main/java/google/registry/flows/domain/DomainDeleteFlow.java b/core/src/main/java/google/registry/flows/domain/DomainDeleteFlow.java
index a0a89811d..379a3df86 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainDeleteFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainDeleteFlow.java
@@ -34,6 +34,7 @@ import static google.registry.model.eppoutput.Result.Code.SUCCESS;
 import static google.registry.model.eppoutput.Result.Code.SUCCESS_WITH_ACTION_PENDING;
 import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.ADD_FIELDS;
 import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.RENEW_FIELDS;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_DELETE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.pricing.PricingEngineProxy.getDomainRenewCost;
 import static google.registry.util.CollectionUtils.nullToEmpty;
@@ -88,7 +89,6 @@ import google.registry.model.registry.Registry;
 import google.registry.model.registry.Registry.TldType;
 import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.DomainTransactionRecord.TransactionReportField;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Collections;
@@ -331,11 +331,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
                       : TransactionReportField.DELETED_DOMAINS_NOGRACE,
                   1)));
     }
-    return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_DELETE)
-        .setModificationTime(now)
-        .setDomain(domain)
-        .build();
+    return historyBuilder.setType(DOMAIN_DELETE).setDomain(domain).build();
   }
 
   private PollMessage.OneTime createDeletePollMessage(
diff --git a/core/src/main/java/google/registry/flows/domain/DomainRenewFlow.java b/core/src/main/java/google/registry/flows/domain/DomainRenewFlow.java
index 05a909e44..a18cc7732 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainRenewFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainRenewFlow.java
@@ -29,6 +29,7 @@ import static google.registry.flows.domain.DomainFlowUtils.validateFeeChallenge;
 import static google.registry.flows.domain.DomainFlowUtils.validateRegistrationPeriod;
 import static google.registry.flows.domain.DomainFlowUtils.verifyRegistrarIsActive;
 import static google.registry.flows.domain.DomainFlowUtils.verifyUnitIsYears;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_RENEW;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.DateTimeUtils.leapSafeAddYears;
 
@@ -73,7 +74,6 @@ import google.registry.model.poll.PollMessage;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.DomainTransactionRecord.TransactionReportField;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import java.util.Optional;
 import javax.inject.Inject;
@@ -230,9 +230,8 @@ public final class DomainRenewFlow implements TransactionalFlow {
   private DomainHistory buildDomainHistory(
       DomainBase newDomain, DateTime now, Period period, Duration renewGracePeriod) {
     return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_RENEW)
+        .setType(DOMAIN_RENEW)
         .setPeriod(period)
-        .setModificationTime(now)
         .setDomain(newDomain)
         .setDomainTransactionRecords(
             ImmutableSet.of(
diff --git a/core/src/main/java/google/registry/flows/domain/DomainRestoreRequestFlow.java b/core/src/main/java/google/registry/flows/domain/DomainRestoreRequestFlow.java
index ddc4de010..bd4016f46 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainRestoreRequestFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainRestoreRequestFlow.java
@@ -27,6 +27,7 @@ import static google.registry.flows.domain.DomainFlowUtils.verifyNotReserved;
 import static google.registry.flows.domain.DomainFlowUtils.verifyPremiumNameIsNotBlocked;
 import static google.registry.flows.domain.DomainFlowUtils.verifyRegistrarIsActive;
 import static google.registry.model.ResourceTransferUtils.updateForeignKeyIndexDeletionTime;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_RESTORE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
 
@@ -66,7 +67,6 @@ import google.registry.model.poll.PollMessage;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.DomainTransactionRecord.TransactionReportField;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import java.util.Optional;
 import javax.inject.Inject;
@@ -188,8 +188,7 @@ public final class DomainRestoreRequestFlow implements TransactionalFlow  {
 
   private DomainHistory buildDomainHistory(DomainBase newDomain, DateTime now) {
     return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_RESTORE)
-        .setModificationTime(now)
+        .setType(DOMAIN_RESTORE)
         .setDomain(newDomain)
         .setDomainTransactionRecords(
             ImmutableSet.of(
diff --git a/core/src/main/java/google/registry/flows/domain/DomainTransferApproveFlow.java b/core/src/main/java/google/registry/flows/domain/DomainTransferApproveFlow.java
index b9fad6717..1d69e892e 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainTransferApproveFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainTransferApproveFlow.java
@@ -29,6 +29,7 @@ import static google.registry.flows.domain.DomainTransferUtils.createGainingTran
 import static google.registry.flows.domain.DomainTransferUtils.createTransferResponse;
 import static google.registry.model.ResourceTransferUtils.approvePendingTransfer;
 import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.TRANSFER_SUCCESSFUL;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_TRANSFER_APPROVE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.pricing.PricingEngineProxy.getDomainRenewCost;
 import static google.registry.util.CollectionUtils.union;
@@ -58,7 +59,6 @@ import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.poll.PollMessage;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferStatus;
@@ -240,8 +240,7 @@ public final class DomainTransferApproveFlow implements TransactionalFlow {
             registry.getAutomaticTransferLength().plus(registry.getTransferGracePeriodLength()),
             ImmutableSet.of(TRANSFER_SUCCESSFUL));
     return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_TRANSFER_APPROVE)
-        .setModificationTime(now)
+        .setType(DOMAIN_TRANSFER_APPROVE)
         .setOtherClientId(gainingClientId)
         .setDomain(newDomain)
         .setDomainTransactionRecords(
diff --git a/core/src/main/java/google/registry/flows/domain/DomainTransferCancelFlow.java b/core/src/main/java/google/registry/flows/domain/DomainTransferCancelFlow.java
index 625d3da1e..22115af42 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainTransferCancelFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainTransferCancelFlow.java
@@ -27,6 +27,7 @@ import static google.registry.flows.domain.DomainTransferUtils.createLosingTrans
 import static google.registry.flows.domain.DomainTransferUtils.createTransferResponse;
 import static google.registry.model.ResourceTransferUtils.denyPendingTransfer;
 import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.TRANSFER_SUCCESSFUL;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_TRANSFER_CANCEL;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
 
@@ -46,7 +47,6 @@ import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
@@ -130,8 +130,7 @@ public final class DomainTransferCancelFlow implements TransactionalFlow {
             registry.getAutomaticTransferLength().plus(registry.getTransferGracePeriodLength()),
             ImmutableSet.of(TRANSFER_SUCCESSFUL));
     return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_TRANSFER_CANCEL)
-        .setModificationTime(now)
+        .setType(DOMAIN_TRANSFER_CANCEL)
         .setDomain(newDomain)
         .setDomainTransactionRecords(cancelingRecords)
         .build();
diff --git a/core/src/main/java/google/registry/flows/domain/DomainTransferRejectFlow.java b/core/src/main/java/google/registry/flows/domain/DomainTransferRejectFlow.java
index 0160288d8..84f5d7355 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainTransferRejectFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainTransferRejectFlow.java
@@ -28,6 +28,7 @@ import static google.registry.flows.domain.DomainTransferUtils.createTransferRes
 import static google.registry.model.ResourceTransferUtils.denyPendingTransfer;
 import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.TRANSFER_NACKED;
 import static google.registry.model.reporting.DomainTransactionRecord.TransactionReportField.TRANSFER_SUCCESSFUL;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_TRANSFER_REJECT;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.CollectionUtils.union;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
@@ -48,7 +49,6 @@ import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.TransferStatus;
 import java.util.Optional;
@@ -131,8 +131,7 @@ public final class DomainTransferRejectFlow implements TransactionalFlow {
             registry.getAutomaticTransferLength().plus(registry.getTransferGracePeriodLength()),
             ImmutableSet.of(TRANSFER_SUCCESSFUL));
     return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_TRANSFER_REJECT)
-        .setModificationTime(now)
+        .setType(DOMAIN_TRANSFER_REJECT)
         .setDomainTransactionRecords(
             union(
                 cancelingRecords,
diff --git a/core/src/main/java/google/registry/flows/domain/DomainTransferRequestFlow.java b/core/src/main/java/google/registry/flows/domain/DomainTransferRequestFlow.java
index 87c4e5792..ef083b927 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainTransferRequestFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainTransferRequestFlow.java
@@ -32,6 +32,7 @@ import static google.registry.flows.domain.DomainTransferUtils.createPendingTran
 import static google.registry.flows.domain.DomainTransferUtils.createTransferResponse;
 import static google.registry.flows.domain.DomainTransferUtils.createTransferServerApproveEntities;
 import static google.registry.model.eppoutput.Result.Code.SUCCESS_WITH_ACTION_PENDING;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_TRANSFER_REQUEST;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableList;
@@ -68,7 +69,6 @@ import google.registry.model.poll.PollMessage;
 import google.registry.model.registry.Registry;
 import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.DomainTransactionRecord.TransactionReportField;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.model.transfer.DomainTransferData;
 import google.registry.model.transfer.TransferData.TransferServerApproveEntity;
@@ -315,9 +315,8 @@ public final class DomainTransferRequestFlow implements TransactionalFlow {
   private DomainHistory buildDomainHistory(
       DomainBase newDomain, Registry registry, DateTime now, Period period) {
     return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_TRANSFER_REQUEST)
+        .setType(DOMAIN_TRANSFER_REQUEST)
         .setPeriod(period)
-        .setModificationTime(now)
         .setDomain(newDomain)
         .setDomainTransactionRecords(
             ImmutableSet.of(
diff --git a/core/src/main/java/google/registry/flows/domain/DomainUpdateFlow.java b/core/src/main/java/google/registry/flows/domain/DomainUpdateFlow.java
index 311577ece..03b260243 100644
--- a/core/src/main/java/google/registry/flows/domain/DomainUpdateFlow.java
+++ b/core/src/main/java/google/registry/flows/domain/DomainUpdateFlow.java
@@ -39,6 +39,7 @@ import static google.registry.flows.domain.DomainFlowUtils.validateRegistrantAll
 import static google.registry.flows.domain.DomainFlowUtils.validateRequiredContactsPresent;
 import static google.registry.flows.domain.DomainFlowUtils.verifyClientUpdateNotProhibited;
 import static google.registry.flows.domain.DomainFlowUtils.verifyNotInPendingDelete;
+import static google.registry.model.reporting.HistoryEntry.Type.DOMAIN_UPDATE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableSet;
@@ -76,7 +77,6 @@ import google.registry.model.eppinput.EppInput;
 import google.registry.model.eppinput.ResourceCommand;
 import google.registry.model.eppoutput.EppResponse;
 import google.registry.model.registry.Registry;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import java.util.Optional;
 import javax.inject.Inject;
@@ -166,7 +166,8 @@ public final class DomainUpdateFlow implements TransactionalFlow {
     flowCustomLogic.afterValidation(
         AfterValidationParameters.newBuilder().setExistingDomain(existingDomain).build());
     DomainBase newDomain = performUpdate(command, existingDomain, now);
-    DomainHistory domainHistory = buildDomainHistory(newDomain, now);
+    DomainHistory domainHistory =
+        historyBuilder.setType(DOMAIN_UPDATE).setDomain(newDomain).build();
     validateNewState(newDomain);
     dnsQueue.addDomainRefreshTask(targetId);
     ImmutableSet.Builder<ImmutableObject> entitiesToSave = new ImmutableSet.Builder<>();
@@ -217,14 +218,6 @@ public final class DomainUpdateFlow implements TransactionalFlow {
         tld, add.getNameserverFullyQualifiedHostNames());
   }
 
-  private DomainHistory buildDomainHistory(DomainBase newDomain, DateTime now) {
-    return historyBuilder
-        .setType(HistoryEntry.Type.DOMAIN_UPDATE)
-        .setModificationTime(now)
-        .setDomain(newDomain)
-        .build();
-  }
-
   private DomainBase performUpdate(Update command, DomainBase domain, DateTime now)
       throws EppException {
     AddRemove add = command.getInnerAdd();
diff --git a/core/src/main/java/google/registry/flows/host/HostCreateFlow.java b/core/src/main/java/google/registry/flows/host/HostCreateFlow.java
index 75fc2ab1e..199159dc6 100644
--- a/core/src/main/java/google/registry/flows/host/HostCreateFlow.java
+++ b/core/src/main/java/google/registry/flows/host/HostCreateFlow.java
@@ -22,6 +22,7 @@ import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomain
 import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomainOwnership;
 import static google.registry.model.EppResourceUtils.createRepoId;
 import static google.registry.model.IdService.allocateId;
+import static google.registry.model.reporting.HistoryEntry.Type.HOST_CREATE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.CollectionUtils.isNullOrEmpty;
 
@@ -50,7 +51,6 @@ import google.registry.model.host.HostHistory;
 import google.registry.model.host.HostResource;
 import google.registry.model.index.EppResourceIndex;
 import google.registry.model.index.ForeignKeyIndex;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import java.util.Optional;
 import javax.inject.Inject;
@@ -129,7 +129,7 @@ public final class HostCreateFlow implements TransactionalFlow {
             .setRepoId(createRepoId(allocateId(), roidSuffix))
             .setSuperordinateDomain(superordinateDomain.map(DomainBase::createVKey).orElse(null))
             .build();
-    historyBuilder.setType(HistoryEntry.Type.HOST_CREATE).setModificationTime(now).setHost(newHost);
+    historyBuilder.setType(HOST_CREATE).setHost(newHost);
     ImmutableSet<ImmutableObject> entitiesToSave =
         ImmutableSet.of(
             newHost,
diff --git a/core/src/main/java/google/registry/flows/host/HostDeleteFlow.java b/core/src/main/java/google/registry/flows/host/HostDeleteFlow.java
index 1456e6ce3..ddf4aaa68 100644
--- a/core/src/main/java/google/registry/flows/host/HostDeleteFlow.java
+++ b/core/src/main/java/google/registry/flows/host/HostDeleteFlow.java
@@ -130,7 +130,7 @@ public final class HostDeleteFlow implements TransactionalFlow {
       historyEntryType = Type.HOST_DELETE;
       resultCode = SUCCESS;
     }
-    historyBuilder.setType(historyEntryType).setModificationTime(now).setHost(newHost);
+    historyBuilder.setType(historyEntryType).setHost(newHost);
     tm().insert(historyBuilder.build());
     tm().update(newHost);
     return responseBuilder.setResultFromCode(resultCode).build();
diff --git a/core/src/main/java/google/registry/flows/host/HostUpdateFlow.java b/core/src/main/java/google/registry/flows/host/HostUpdateFlow.java
index e8395b3c3..3d2f3d774 100644
--- a/core/src/main/java/google/registry/flows/host/HostUpdateFlow.java
+++ b/core/src/main/java/google/registry/flows/host/HostUpdateFlow.java
@@ -27,6 +27,7 @@ import static google.registry.flows.host.HostFlowUtils.validateHostName;
 import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomainNotInPendingDelete;
 import static google.registry.flows.host.HostFlowUtils.verifySuperordinateDomainOwnership;
 import static google.registry.model.index.ForeignKeyIndex.loadAndGetKey;
+import static google.registry.model.reporting.HistoryEntry.Type.HOST_UPDATE;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.CollectionUtils.isNullOrEmpty;
 
@@ -57,7 +58,6 @@ import google.registry.model.host.HostCommand.Update.Change;
 import google.registry.model.host.HostHistory;
 import google.registry.model.host.HostResource;
 import google.registry.model.index.ForeignKeyIndex;
-import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.reporting.IcannReportingTypes.ActivityReportField;
 import google.registry.persistence.VKey;
 import java.util.Objects;
@@ -201,12 +201,7 @@ public final class HostUpdateFlow implements TransactionalFlow {
       updateSuperordinateDomains(existingHost, newHost);
     }
     enqueueTasks(existingHost, newHost);
-    entitiesToInsert.add(
-        historyBuilder
-            .setType(HistoryEntry.Type.HOST_UPDATE)
-            .setModificationTime(now)
-            .setHost(newHost)
-            .build());
+    entitiesToInsert.add(historyBuilder.setType(HOST_UPDATE).setHost(newHost).build());
     tm().updateAll(entitiesToUpdate.build());
     tm().insertAll(entitiesToInsert.build());
     return responseBuilder.build();