diff --git a/legal-api/src/legal_api/resources/v2/business/business_tasks.py b/legal-api/src/legal_api/resources/v2/business/business_tasks.py
index 2e28b1bdb1..9899419a16 100644
--- a/legal-api/src/legal_api/resources/v2/business/business_tasks.py
+++ b/legal-api/src/legal_api/resources/v2/business/business_tasks.py
@@ -151,7 +151,16 @@ def construct_task_list(business: Business):  # noqa: PLR0915
         tasks.append(task)
         order += 1
 
-    if business.legal_type not in entity_types_no_ar and not business.in_liquidation:
+    # Skip AR todos when founding date is the COLIN year 0001 (for legacy data like railways). Without this,
+    # a sentinel founding_date of 0001-01-01 generates ~2000 AR todos and a multi-MB /tasks payload.
+    unknown_founding_date = (
+        not business.founding_date or business.founding_date.year <= 1
+    )
+    if (
+        business.legal_type not in entity_types_no_ar
+        and not business.in_liquidation
+        and not unknown_founding_date
+    ):
         # If this is the first calendar year since incorporation, there is no previous ar year.
         next_ar_year = (business.last_ar_year if business.last_ar_year else business.founding_date.year) + 1
 
diff --git a/legal-api/tests/unit/resources/v2/test_business_tasks.py b/legal-api/tests/unit/resources/v2/test_business_tasks.py
index 2c04f942c7..d7e21095a6 100644
--- a/legal-api/tests/unit/resources/v2/test_business_tasks.py
+++ b/legal-api/tests/unit/resources/v2/test_business_tasks.py
@@ -94,7 +94,26 @@ def test_get_tasks_no_filings(session, client, jwt):
 
     rv = client.get(f'/api/v2/businesses/{identifier}/tasks', headers=create_header(jwt, [STAFF_ROLE], identifier))
     assert rv.status_code == HTTPStatus.OK
-    assert num_filings_owed == len(rv.json.get('tasks'))
+    assert len(rv.json.get('tasks')) == num_filings_owed
+
+
+def test_get_tasks_sentinel_founding_date_skips_ar(session, client, jwt):
+    """Assert COLIN year-1 sentinel founding date does not generate thousands of AR todos."""
+    identifier = 'BC1234567'
+    factory_business(
+        identifier,
+        founding_date=datetime(1, 1, 1, 8, 0, 0, tzinfo=UTC),
+        entity_type=Business.LegalTypes.COMP.value,
+        state=Business.State.ACTIVE,
+    )
+
+    rv = client.get(f'/api/v2/businesses/{identifier}/tasks', headers=create_header(jwt, [STAFF_ROLE], identifier))
+    assert rv.status_code == HTTPStatus.OK
+    ar_tasks = [
+        t for t in rv.json.get('tasks')
+        if t.get('task', {}).get('todo', {}).get('header', {}).get('name') == 'annualReport'
+    ]
+    assert len(ar_tasks) == 0
 
 
 def test_get_tasks_next_year(session, client, jwt):
@@ -107,7 +126,7 @@ def test_get_tasks_next_year(session, client, jwt):
 
     rv = client.get(f'/api/v2/businesses/{identifier}/tasks', headers=create_header(jwt, [STAFF_ROLE], identifier))
     assert rv.status_code == HTTPStatus.OK
-    assert 1 == len(rv.json.get('tasks'))
+    assert len(rv.json.get('tasks')) == 1
 
 
 def test_bcorps_get_tasks_no_filings(session, client, jwt):