diff --git a/enterprise_subsidy/apps/api/v1/serializers.py b/enterprise_subsidy/apps/api/v1/serializers.py
index c102c4ce..aff4185f 100644
--- a/enterprise_subsidy/apps/api/v1/serializers.py
+++ b/enterprise_subsidy/apps/api/v1/serializers.py
@@ -28,7 +28,7 @@ class SubsidySerializer(serializers.ModelSerializer):
     """
     current_balance = serializers.SerializerMethodField(help_text="The current (remaining) balance of this subsidy.")
     is_active = serializers.BooleanField(read_only=True, help_text="Whether this subsidy is currently active.")
-    total_deposits = serializers.SerializerMethodField(
+    total_deposits = serializers.IntegerField(
         help_text="The aggregate of the initial balance plus all adjustments made on the subsidy in usd cents"
     )
 
@@ -68,10 +68,6 @@ class Meta:
     def get_current_balance(self, obj) -> int:
         return obj.current_balance()
 
-    @extend_schema_field(serializers.IntegerField)
-    def get_total_deposits(self, obj) -> int:
-        return obj.total_deposits()
-
 
 class ReversalSerializer(serializers.ModelSerializer):
     """
diff --git a/enterprise_subsidy/apps/api/v1/tests/test_views.py b/enterprise_subsidy/apps/api/v1/tests/test_views.py
index 2d74898a..d1f534d7 100644
--- a/enterprise_subsidy/apps/api/v1/tests/test_views.py
+++ b/enterprise_subsidy/apps/api/v1/tests/test_views.py
@@ -274,7 +274,7 @@ def test_get_adjustments_related_subsidy(self):
             "internal_only": False,
             "revenue_category": RevenueCategoryChoices.BULK_ENROLLMENT_PREPAY,
             "is_active": True,
-            "total_deposits": self.subsidy_5.total_deposits(),
+            "total_deposits": self.subsidy_5.total_deposits,
         }
         total_deposits_including_positive_adjustment = sum(
             [self.subsidy_5.starting_balance, APITestBase.adjustment_quantity_1]
@@ -312,7 +312,7 @@ def test_get_adjustments_related_subsidy(self):
             "internal_only": False,
             "revenue_category": RevenueCategoryChoices.BULK_ENROLLMENT_PREPAY,
             "is_active": True,
-            "total_deposits": self.subsidy_5.total_deposits(),
+            "total_deposits": self.subsidy_5.total_deposits,
         }
 
         total_deposits_including_negative_adjustment = sum(
diff --git a/enterprise_subsidy/apps/subsidy/migration_utils.py b/enterprise_subsidy/apps/subsidy/migration_utils.py
new file mode 100644
index 00000000..8f031ef3
--- /dev/null
+++ b/enterprise_subsidy/apps/subsidy/migration_utils.py
@@ -0,0 +1,40 @@
+"""
+Helper functions for data migrations.
+"""
+from django.db.models import F, Window
+from django.db.models.functions import FirstValue
+# This utils module is imported by migrations, so never import any models directly here, nor any modules that import
+# models in turn.
+from openedx_ledger.constants import INITIAL_DEPOSIT_TRANSACTION_SLUG
+
+
+def find_legacy_initial_transactions(transaction_cls):
+    """
+    Heuristic to identify "legacy" initial transactions.
+
+    An initial transaction is one that has the following traits:
+    * Is chronologically the first transaction for a Ledger.
+    * Contains a hint in its idempotency key which indicates that it is an initial deposit.
+    * Has a positive quantity.
+
+    A legacy initial transaction is one that has the following additional traits:
+    * does not have a related Deposit.
+    """
+    # All transactions which are chronologically the first in their respective ledgers.
+    first_transactions = transaction_cls.objects.annotate(
+        first_tx_uuid=Window(
+            expression=FirstValue('uuid'),
+            partition_by=['ledger'],
+            order_by=F('created').asc(),  # "first chronologically" above means first created.
+        ),
+    ).filter(uuid=F('first_tx_uuid'))
+
+    # Further filter first_transactions to find ones that qualify as _initial_ and _legacy_.
+    legacy_initial_transactions = first_transactions.filter(
+        # Traits of an _initial_ deposit:
+        idempotency_key__contains=INITIAL_DEPOSIT_TRANSACTION_SLUG,
+        quantity__gte=0,
+        # Traits of a _legacy_ initial deposit:
+        deposit__isnull=True,
+    )
+    return legacy_initial_transactions
diff --git a/enterprise_subsidy/apps/subsidy/migrations/0022_backfill_initial_deposits.py b/enterprise_subsidy/apps/subsidy/migrations/0022_backfill_initial_deposits.py
new file mode 100644
index 00000000..121c0678
--- /dev/null
+++ b/enterprise_subsidy/apps/subsidy/migrations/0022_backfill_initial_deposits.py
@@ -0,0 +1,83 @@
+"""
+Backfill initial deposits.
+
+Necessarily, this also backfills SalesContractReferenceProvider objects based on the values currently defined via
+SubsidyReferenceChoices.
+
+Note this has no reverse migration logic. Attempts to rollback the deployment which includes this PR will not delete
+(un-backfill) the deposits created during the forward migration.
+"""
+import django.utils.timezone
+from django.db import migrations
+
+from enterprise_subsidy.apps.subsidy.migration_utils import find_legacy_initial_transactions
+from enterprise_subsidy.apps.subsidy.models import SubsidyReferenceChoices
+
+
+def forwards_func(apps, schema_editor):
+    """
+    The core logic of this migration.
+    """
+    # We get the models from the versioned app registry; if we directly import it, it'll be the wrong version.
+    Transaction = apps.get_model("openedx_ledger", "Transaction")
+    Deposit = apps.get_model("openedx_ledger", "Deposit")
+    HistoricalDeposit = apps.get_model("openedx_ledger", "HistoricalDeposit")
+    SalesContractReferenceProvider = apps.get_model("openedx_ledger", "SalesContractReferenceProvider")
+
+    # Idempotently duplicate all SubsidyReferenceChoices into SalesContractReferenceProvider.
+    sales_contract_reference_providers = {}
+    for slug, name in SubsidyReferenceChoices.CHOICES:
+        sales_contract_reference_providers[slug], _ = SalesContractReferenceProvider.objects.get_or_create(
+            slug=slug,
+            defaults={"name": name},
+        )
+
+    # Fetch all "legacy" initial transactions.
+    legacy_initial_transactions = find_legacy_initial_transactions(Transaction).select_related("ledger__subsidy")
+
+    # Construct all missing Deposits and HistoricalDeposits to backfill, but do not save them yet.
+    #
+    # Note: The reason we need to manually create historical objects is that Django's bulk_create() built-in does not
+    # call post_save hooks, which is normally where history objects are created. Next you might ask why we don't just
+    # use django-simple-history's bulk_create_with_history() utility function: that's because it attempts to access the
+    # custom simple history model manager, but unfortunately custom model attributes are unavailable from migrations.
+    deposits_to_backfill = []
+    historical_deposits_to_backfill = []
+    for tx in legacy_initial_transactions:
+        deposit_fields = {
+            "ledger": tx.ledger,
+            "transaction": tx,
+            "desired_deposit_quantity": tx.quantity,
+            "sales_contract_reference_id": tx.ledger.subsidy.reference_id,
+            "sales_contract_reference_provider": sales_contract_reference_providers[tx.ledger.subsidy.reference_type],
+        }
+        deposit = Deposit(**deposit_fields)
+        historical_deposit = HistoricalDeposit(
+            uuid=deposit.uuid,
+            history_date=django.utils.timezone.now(),
+            history_type="+",
+            history_change_reason="Data migration to backfill initial deposits",
+            **deposit_fields,
+        )
+        deposits_to_backfill.append(deposit)
+        historical_deposits_to_backfill.append(historical_deposit)
+
+    # Finally, save the missing Deposits and HistoricalDeposits in bulk.
+    Deposit.objects.bulk_create(deposits_to_backfill, batch_size=50)
+    HistoricalDeposit.objects.bulk_create(historical_deposits_to_backfill, batch_size=50)
+
+
+class Migration(migrations.Migration):
+    """
+    Migration for backfilling initial deposits.
+    """
+    dependencies = [
+        ("subsidy", "0021_alter_historicalsubsidy_options"),
+        # This migration relies on Deposit.sales_contract_reference_id being an optional field. Django alone cannot
+        # possibly know about this dependency without our help.
+        ("openedx_ledger", "0012_optional_deposit_sales_contract_reference"),
+    ]
+
+    operations = [
+        migrations.RunPython(forwards_func),
+    ]
diff --git a/enterprise_subsidy/apps/subsidy/models.py b/enterprise_subsidy/apps/subsidy/models.py
index 3d56b651..4dea4241 100644
--- a/enterprise_subsidy/apps/subsidy/models.py
+++ b/enterprise_subsidy/apps/subsidy/models.py
@@ -21,7 +21,7 @@
 from edx_rbac.utils import ALL_ACCESS_CONTEXT
 from model_utils.models import TimeStampedModel
 from openedx_ledger import api as ledger_api
-from openedx_ledger.models import Adjustment, Ledger, TransactionStateChoices, UnitChoices
+from openedx_ledger.models import Ledger, TransactionStateChoices, UnitChoices
 from openedx_ledger.utils import create_idempotency_key_for_transaction
 from requests.exceptions import HTTPError
 from rest_framework import status
@@ -115,6 +115,8 @@ class Meta:
         Metaclass for Subsidy.
         """
         ordering = ['-created']
+        verbose_name = 'Subsidy'
+        verbose_name_plural = 'Subsidies'
 
     # Please reserve the "subsidy_type" field name for the future when we use it to distinguish between
     # LearnerCreditSubsidy vs. SubscriptionSubsidy.
@@ -350,19 +352,18 @@ def price_for_content(self, content_key):
     def current_balance(self):
         return self.ledger.balance()
 
+    @property
     def total_deposits(self):
         """
-        Returns the sum of all adjustments for the subsidy + the starting balance in USD cents.
+        Returns the sum of all value added to the subsidy.
+
+        At the time of writing, this includes both deposits AND adjustments, as both are essentially meant to augment
+        the value added to the subsidy.
 
         Returns:
-            int: Sum of all adjustments and the starting balance in USD cents.
-        """
-        adjustments_for_subsidy = Adjustment.objects.filter(ledger=self.ledger)
-        total_deposits = sum([
-            adjustment.transaction.quantity
-            for adjustment in adjustments_for_subsidy
-        ], self.starting_balance)
-        return total_deposits
+            int: Sum of all value added to the subsidy, in USD cents.
+        """
+        return self.ledger.total_deposits()
 
     def create_transaction(
         self,
diff --git a/enterprise_subsidy/apps/subsidy/signals.py b/enterprise_subsidy/apps/subsidy/signals.py
index 28eff8b1..22bad383 100644
--- a/enterprise_subsidy/apps/subsidy/signals.py
+++ b/enterprise_subsidy/apps/subsidy/signals.py
@@ -4,8 +4,9 @@
 from django.db.models.signals import pre_save
 from django.dispatch import receiver
 from openedx_ledger.api import create_ledger
+from openedx_ledger.models import SalesContractReferenceProvider
 
-from .models import Subsidy
+from .models import Subsidy, SubsidyReferenceChoices
 
 
 @receiver(pre_save, sender=Subsidy)
@@ -21,6 +22,16 @@ def subsidy_pre_save(sender, instance, *args, **kwargs):  # pylint: disable=unus
     if instance.ledger or not instance._state.adding:
         return
 
+    # In order to call create_ledger() later, we first need to get or create a SalesContractReferenceProvider. In order
+    # to avoid manual intervention, we mirror the SubsidyReferenceChoices selection into the
+    # SalesContractReferenceProvider table as needed. The normal steady-state is to always just re-use (get) an existing
+    # provider.
+    subsidy_reference_choices = dict((slug, name) for slug, name in SubsidyReferenceChoices.CHOICES)
+    sales_contract_reference_provider, _ = SalesContractReferenceProvider.objects.get_or_create(
+        slug=instance.reference_type,
+        defaults={"name": subsidy_reference_choices[instance.reference_type]},
+    )
+
     # create_ledger() saves the ledger instance.
     # If a transaction for the starting_balance is created,
     # that transaction record is also saved during
@@ -29,4 +40,6 @@ def subsidy_pre_save(sender, instance, *args, **kwargs):  # pylint: disable=unus
         unit=instance.unit,
         subsidy_uuid=instance.uuid,
         initial_deposit=instance.starting_balance,
+        sales_contract_reference_id=instance.reference_id,
+        sales_contract_reference_provider=sales_contract_reference_provider,
     )
diff --git a/enterprise_subsidy/apps/subsidy/tests/test_migration_utils.py b/enterprise_subsidy/apps/subsidy/tests/test_migration_utils.py
new file mode 100644
index 00000000..a9d2eb77
--- /dev/null
+++ b/enterprise_subsidy/apps/subsidy/tests/test_migration_utils.py
@@ -0,0 +1,53 @@
+"""
+Tests for the migration_utils.py module.
+"""
+from django.test import TestCase
+from openedx_ledger.constants import INITIAL_DEPOSIT_TRANSACTION_SLUG
+from openedx_ledger.models import Transaction
+from openedx_ledger.test_utils.factories import AdjustmentFactory, DepositFactory, LedgerFactory, TransactionFactory
+
+from enterprise_subsidy.apps.subsidy import migration_utils
+
+
+class MigrationUtilsTests(TestCase):
+    """
+    Tests for utils used for migrations.
+    """
+    def test_find_legacy_initial_transactions(self):
+        """
+        Test find_legacy_initial_transactions(), used for a data migration to backfill initial deposits.
+        """
+        ledgers = [
+            (LedgerFactory(), False),
+            (LedgerFactory(), False),
+            (LedgerFactory(), True),
+            (LedgerFactory(), False),
+            (LedgerFactory(), True),
+        ]
+        expected_legacy_initial_transactions = []
+        for ledger, create_initial_deposit in ledgers:
+            # Simulate a legacy initial transaction (i.e. transaction WITHOUT a deposit).
+            initial_transaction = TransactionFactory(
+                ledger=ledger,
+                idempotency_key=INITIAL_DEPOSIT_TRANSACTION_SLUG,
+                quantity=100,
+            )
+            if create_initial_deposit:
+                # Make it a modern initial deposit by creating a related Deposit.
+                DepositFactory(
+                    ledger=ledger,
+                    transaction=initial_transaction,
+                    desired_deposit_quantity=initial_transaction.quantity,
+                )
+            else:
+                # Keep it a legacy initial deposit by NOT creating a related Deposit.
+                expected_legacy_initial_transactions.append(initial_transaction)
+            # Throw in a few spend, deposit, and adjustment transactions for fun.
+            TransactionFactory(ledger=ledger, quantity=-10)
+            TransactionFactory(ledger=ledger, quantity=-10)
+            DepositFactory(ledger=ledger, desired_deposit_quantity=50)
+            tx_to_adjust = TransactionFactory(ledger=ledger, quantity=-5)
+            AdjustmentFactory(ledger=ledger, adjustment_quantity=5, transaction_of_interest=tx_to_adjust)
+
+        actual_legacy_initial_transactions = migration_utils.find_legacy_initial_transactions(Transaction)
+        assert set(actual_legacy_initial_transactions) == set(expected_legacy_initial_transactions)
diff --git a/enterprise_subsidy/apps/subsidy/tests/test_migrations.py b/enterprise_subsidy/apps/subsidy/tests/test_migrations.py
new file mode 100644
index 00000000..6add9813
--- /dev/null
+++ b/enterprise_subsidy/apps/subsidy/tests/test_migrations.py
@@ -0,0 +1,96 @@
+"""
+Test migrations.
+"""
+import uuid
+
+import django.utils.timezone
+import pytest
+from openedx_ledger.constants import INITIAL_DEPOSIT_TRANSACTION_SLUG
+from openedx_ledger.models import TransactionStateChoices
+
+
+@pytest.mark.django_db
+@pytest.mark.parametrize(
+    "initial_deposit_exists,subsidy_reference_id",
+    [
+        (False, None),
+        (False, "abc123"),
+        (True, None),
+        (True, "abc123"),
+    ],
+)
+def test_migration_0022_backfill_initial_deposits(migrator, initial_deposit_exists, subsidy_reference_id):
+    """
+    Test Backfilling initial deposits via data migration.
+    """
+    old_state = migrator.apply_initial_migration([
+        ("subsidy", "0021_alter_historicalsubsidy_options"),
+        ("openedx_ledger", "0012_optional_deposit_sales_contract_reference"),
+    ])
+
+    Subsidy = old_state.apps.get_model("subsidy", "Subsidy")
+    Ledger = old_state.apps.get_model("openedx_ledger", "Ledger")
+    Transaction = old_state.apps.get_model("openedx_ledger", "Transaction")
+    Deposit = old_state.apps.get_model("openedx_ledger", "Deposit")
+    HistoricalDeposit = old_state.apps.get_model("openedx_ledger", "HistoricalDeposit")
+    SalesContractReferenceProvider = old_state.apps.get_model("openedx_ledger", "SalesContractReferenceProvider")
+
+    ledger = Ledger.objects.create()
+    subsidy = Subsidy.objects.create(
+        ledger=ledger,
+        starting_balance=100,
+        reference_id=subsidy_reference_id,
+        enterprise_customer_uuid=uuid.uuid4(),
+    )
+    transaction = Transaction.objects.create(
+        ledger=ledger,
+        idempotency_key=INITIAL_DEPOSIT_TRANSACTION_SLUG,
+        quantity=subsidy.starting_balance,
+        state=TransactionStateChoices.COMMITTED
+    )
+    if initial_deposit_exists:
+        sales_contract_reference_provider = SalesContractReferenceProvider.objects.create(
+            slug=subsidy.reference_type,
+            name="Foo Bar",
+        )
+        Deposit.objects.create(
+            ledger=ledger,
+            desired_deposit_quantity=transaction.quantity,
+            transaction=transaction,
+            sales_contract_reference_id=subsidy_reference_id,  # Sometimes this is None.
+            sales_contract_reference_provider=sales_contract_reference_provider,
+        )
+        HistoricalDeposit.objects.create(
+            ledger=ledger,
+            desired_deposit_quantity=transaction.quantity,
+            transaction=transaction,
+            sales_contract_reference_id=subsidy_reference_id,
+            sales_contract_reference_provider=sales_contract_reference_provider,
+            history_date=django.utils.timezone.now(),
+            history_type="+",
+            history_change_reason="Data migration to backfill initial deposits",
+        )
+
+    new_state = migrator.apply_tested_migration(
+        ("subsidy", "0022_backfill_initial_deposits"),
+    )
+    Deposit = new_state.apps.get_model("openedx_ledger", "Deposit")
+    HistoricalDeposit = new_state.apps.get_model("openedx_ledger", "HistoricalDeposit")
+
+    # Make sure there is exactly one deposit, suggesting that if one already existed it is not re-created.
+    assert Deposit.objects.all().count() == 1
+    assert HistoricalDeposit.objects.all().count() == 1
+
+    # Finally check that all the deposit values are correct.
+    assert Deposit.objects.first().ledger.uuid == ledger.uuid
+    assert Deposit.objects.first().desired_deposit_quantity == subsidy.starting_balance
+    assert Deposit.objects.first().transaction.uuid == transaction.uuid
+    assert Deposit.objects.first().sales_contract_reference_id == subsidy_reference_id
+    assert Deposit.objects.first().sales_contract_reference_provider.slug == subsidy.reference_type
+    assert HistoricalDeposit.objects.first().ledger.uuid == ledger.uuid
+    assert HistoricalDeposit.objects.first().desired_deposit_quantity == subsidy.starting_balance
+    assert HistoricalDeposit.objects.first().transaction.uuid == transaction.uuid
+    assert HistoricalDeposit.objects.first().sales_contract_reference_id == subsidy_reference_id
+    assert HistoricalDeposit.objects.first().sales_contract_reference_provider.slug == subsidy.reference_type
+    assert HistoricalDeposit.objects.first().history_type == "+"
+    assert HistoricalDeposit.objects.first().history_change_reason == "Data migration to backfill initial deposits"
diff --git a/requirements/base.txt b/requirements/base.txt
index becb2a09..b018e8a2 100644
--- a/requirements/base.txt
+++ b/requirements/base.txt
@@ -199,7 +199,7 @@ openedx-events==9.11.0
     #   -r requirements/base.in
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via -r requirements/base.in
 packaging==24.1
     # via drf-yasg
diff --git a/requirements/dev.txt b/requirements/dev.txt
index 3686cdb7..0dbfb796 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -169,6 +169,8 @@ django-simple-history==3.4.0
     # via
     #   -r requirements/validation.txt
     #   openedx-ledger
+django-test-migrations==1.4.0
+    # via -r requirements/validation.txt
 django-waffle==4.1.0
     # via
     #   -r requirements/validation.txt
@@ -377,7 +379,7 @@ openedx-events==9.11.0
     #   -r requirements/validation.txt
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via -r requirements/validation.txt
 packaging==24.1
     # via
diff --git a/requirements/doc.txt b/requirements/doc.txt
index 77635198..9b1a88a6 100644
--- a/requirements/doc.txt
+++ b/requirements/doc.txt
@@ -358,7 +358,7 @@ openedx-events==9.11.0
     #   -r requirements/test.txt
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via -r requirements/test.txt
 packaging==24.1
     # via
diff --git a/requirements/production.txt b/requirements/production.txt
index 7acddc68..0095298e 100644
--- a/requirements/production.txt
+++ b/requirements/production.txt
@@ -244,7 +244,7 @@ openedx-events==9.11.0
     #   -r requirements/base.txt
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via -r requirements/base.txt
 packaging==24.1
     # via
diff --git a/requirements/quality.txt b/requirements/quality.txt
index ef033acf..b58ff340 100644
--- a/requirements/quality.txt
+++ b/requirements/quality.txt
@@ -339,7 +339,7 @@ openedx-events==9.11.0
     #   -r requirements/test.txt
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via -r requirements/test.txt
 packaging==24.1
     # via
diff --git a/requirements/test.in b/requirements/test.in
index ff279994..fd499473 100644
--- a/requirements/test.in
+++ b/requirements/test.in
@@ -7,6 +7,7 @@ code-annotations
 coverage
 ddt
 django-dynamic-fixture    # library to create dynamic model instances for testing purposes
+django-test-migrations    # For unit testing data migrations
 edx-lint
 factory-boy
 mock
diff --git a/requirements/test.txt b/requirements/test.txt
index f696d1d4..d7b472b9 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -140,6 +140,8 @@ django-simple-history==3.4.0
     #   -c requirements/constraints.txt
     #   -r requirements/base.txt
     #   openedx-ledger
+django-test-migrations==1.4.0
+    # via -r requirements/test.in
 django-waffle==4.1.0
     # via
     #   -r requirements/base.txt
@@ -285,7 +287,7 @@ openedx-events==9.11.0
     #   -r requirements/base.txt
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via -r requirements/base.txt
 packaging==24.1
     # via
diff --git a/requirements/validation.txt b/requirements/validation.txt
index b83dc1f8..99ce8c3f 100644
--- a/requirements/validation.txt
+++ b/requirements/validation.txt
@@ -435,7 +435,7 @@ openedx-events==9.11.0
     #   -r requirements/test.txt
     #   edx-event-bus-kafka
     #   openedx-ledger
-openedx-ledger==1.5.1
+openedx-ledger==1.5.3
     # via
     #   -r requirements/quality.txt
     #   -r requirements/test.txt