diff --git a/api/tests/test_intercompany_matrix.py b/api/tests/test_intercompany_matrix.py
index aaef320..d417d72 100644
--- a/api/tests/test_intercompany_matrix.py
+++ b/api/tests/test_intercompany_matrix.py
@@ -174,6 +174,40 @@ async def test_preset_applies_exclusions_to_its_own_side_and_rule_measure(monkey
     assert info.article_2_line == rule.article_2_line
 
 
+async def test_preset_credit_first_uses_second_side_for_debit(monkeypatch: pytest.MonkeyPatch) -> None:
+    credit_parent = _account(AccountKind.P)
+    credit_child = _account(AccountKind.P, credit_parent.id)
+    debit_parent = _account(AccountKind.A)
+    debit_child = _account(AccountKind.A, debit_parent.id)
+    accounts = [credit_parent, credit_child, debit_parent, debit_child]
+    by_id, children = matrix._make_account_tree(accounts)
+    rule = SimpleNamespace(
+        version_no=1,
+        valid_to=None,
+        statement_type=StatementType.balance,
+        side_1="K",
+        measure="turnover",
+    )
+    rule_accounts = [
+        SimpleNamespace(company_no=1, account_id=credit_parent.id, is_excluded=False),
+        SimpleNamespace(company_no=1, account_id=credit_child.id, is_excluded=True),
+        SimpleNamespace(company_no=2, account_id=debit_parent.id, is_excluded=False),
+    ]
+    monkeypatch.setattr(
+        matrix.elimination_rules_repo, "rule_with_account", AsyncMock(return_value=(rule, rule_accounts))
+    )
+    service = matrix.IntercompanyMatrixService(object(), None, object())
+
+    selection, selected_rule = await service._resolve_preset_selection(
+        uuid.uuid4(), SimpleNamespace(elimination_rules_version=1), by_id, children
+    )
+
+    assert selected_rule is rule
+    assert selection.company_1_account_ids == {debit_parent.id, debit_child.id}
+    assert selection.company_2_account_ids == {credit_parent.id}
+    assert selection.measure == "turnover"
+
+
 async def test_preset_rejects_income_rule_before_selecting_accounts(monkeypatch: pytest.MonkeyPatch) -> None:
     rule = SimpleNamespace(
         statement_type=StatementType.income,