diff --git a/mis_builder_budget/models/mis_report_instance.py b/mis_builder_budget/models/mis_report_instance.py
index 5a095031..da3207ec 100644
--- a/mis_builder_budget/models/mis_report_instance.py
+++ b/mis_builder_budget/models/mis_report_instance.py
@@ -1,7 +1,7 @@
 # Copyright 2017 ACSONE SA/NV
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo import models
+from odoo import api, models
 from odoo.osv.expression import AND
 
 from odoo.addons.mis_builder.models.accounting_none import AccountingNone
@@ -21,10 +21,23 @@ def __init__(self, date_from, date_to, kpi_data, additional_move_line_filter):
         )
         self.kpi_data = kpi_data
 
+    @api.model
+    def _get_kpi_for_expressions(self, expressions):
+        kpi = None
+        for expression in expressions:
+            if not expression:
+                continue
+            if kpi is None:
+                kpi = expression.kpi_id
+            else:
+                assert (
+                    kpi == expression.kpi_id
+                ), "expressions must belong to the same kpi"
+        return kpi
+
     def eval_expressions(self, expressions, locals_dict):
-        kpi_id = expressions.mapped("kpi_id")
-        assert len(kpi_id) == 1
-        if kpi_id.budgetable:
+        kpi = self._get_kpi_for_expressions(expressions)
+        if kpi and kpi.budgetable:
             vals = []
             drilldown_args = []
             for expression in expressions:
diff --git a/mis_builder_budget/readme/newsfragments/428.bugfix b/mis_builder_budget/readme/newsfragments/428.bugfix
new file mode 100644
index 00000000..36ee4177
--- /dev/null
+++ b/mis_builder_budget/readme/newsfragments/428.bugfix
@@ -0,0 +1 @@
+Fix display of budgets in presence of sub KPIs.
diff --git a/mis_builder_budget/tests/__init__.py b/mis_builder_budget/tests/__init__.py
index 699440c2..08d8a279 100644
--- a/mis_builder_budget/tests/__init__.py
+++ b/mis_builder_budget/tests/__init__.py
@@ -1,2 +1,3 @@
+from . import test_expression_evaluator
 from . import test_mis_budget
 from . import test_mis_budget_by_account
diff --git a/mis_builder_budget/tests/test_expression_evaluator.py b/mis_builder_budget/tests/test_expression_evaluator.py
new file mode 100644
index 00000000..07a1f23c
--- /dev/null
+++ b/mis_builder_budget/tests/test_expression_evaluator.py
@@ -0,0 +1,68 @@
+# Copyright 2023 ACSONE SA/NV (<http://acsone.eu>)
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl.html).
+
+from odoo.tests.common import SavepointCase
+
+from odoo.addons.mis_builder_budget.models.mis_report_instance import (
+    MisBudgetAwareExpressionEvaluator,
+)
+
+
+class TestBudgetAwareExpressionEvaluator(SavepointCase):
+    def _make_evaluator(self, kpi_data=None):
+        return MisBudgetAwareExpressionEvaluator(
+            date_from="2017-01-01",
+            date_to="2017-01-16",
+            kpi_data=kpi_data or {},
+            additional_move_line_filter=[],
+        )
+
+    def test_no_expression(self):
+        evaluator = self._make_evaluator()
+        evaluator.eval_expressions([None], locals_dict={})
+
+    def test_one_expression(self):
+        evaluator = self._make_evaluator()
+        kpi = self.env["mis.report.kpi"].new({"name": "thekpi"})
+        expr = self.env["mis.report.kpi.expression"].new(
+            {"kpi_id": kpi.id, "name": "a"}
+        )
+        vals, drilldown_args, name_error = evaluator.eval_expressions(
+            [expr], locals_dict={"a": 1}
+        )
+        self.assertEqual(vals, [1])
+        self.assertEqual(drilldown_args, [None])
+        self.assertFalse(name_error)
+
+    def test_two_expressions(self):
+        evaluator = self._make_evaluator()
+        kpi = self.env["mis.report.kpi"].new({"name": "thekpi"})
+        expr1 = self.env["mis.report.kpi.expression"].new(
+            {"kpi_id": kpi.id, "name": "a"}
+        )
+        expr2 = self.env["mis.report.kpi.expression"].new(
+            {"kpi_id": kpi.id, "name": "b"}
+        )
+        vals, drilldown_args, _ = evaluator.eval_expressions(
+            [expr1, expr2], locals_dict={"a": 1, "b": 2}
+        )
+        self.assertEqual(vals, [1, 2])
+        self.assertEqual(drilldown_args, [None, None])
+
+    def test_two_expressions_with_budget(self):
+        kpi = self.env["mis.report.kpi"].new({"name": "thekpi", "budgetable": True})
+        expr1 = self.env["mis.report.kpi.expression"].new(
+            {"kpi_id": kpi.id, "name": "a"}
+        )
+        expr2 = self.env["mis.report.kpi.expression"].new(
+            {"kpi_id": kpi.id, "name": "b"}
+        )
+        kpi_data = {
+            expr1: 10,
+            expr2: 20,
+        }
+        evaluator = self._make_evaluator(kpi_data)
+        vals, _, _ = evaluator.eval_expressions(
+            [expr1, expr2], locals_dict={"a": 1, "b": 2}
+        )
+        self.assertEqual(vals, [10, 20])  # budget values instead of locals_dict values