diff --git a/app/models/budget_category.rb b/app/models/budget_category.rb
index 27d999703..85c355861 100644
--- a/app/models/budget_category.rb
+++ b/app/models/budget_category.rb
@@ -209,6 +209,7 @@ class BudgetCategory < ApplicationRecord
 
   def subcategories
     return BudgetCategory.none unless category.parent_id.nil?
+    return BudgetCategory.none if category.id.nil?
 
     budget.budget_categories
       .joins(:category)
diff --git a/test/models/budget_category_test.rb b/test/models/budget_category_test.rb
index 61335265e..4e16c4f88 100644
--- a/test/models/budget_category_test.rb
+++ b/test/models/budget_category_test.rb
@@ -162,6 +162,15 @@ class BudgetCategoryTest < ActiveSupport::TestCase
     assert_equal 40.0, standalone_bc.percent_of_budget_spent
   end
 
+  test "uncategorized budget category returns no subcategories" do
+    uncategorized_bc = BudgetCategory.uncategorized
+    uncategorized_bc.budget = @budget
+
+    # Before the fix, this would return all top-level categories because
+    # category.id is nil, causing WHERE parent_id IS NULL to match all roots
+    assert_empty uncategorized_bc.subcategories
+  end
+
   test "parent with only inheriting subcategories shares entire budget" do
     # Set subcategory_with_limit to also inherit
     @subcategory_with_limit_bc.update!(budgeted_spending: 0)