diff --git a/test/aggregate_test.exs b/test/aggregate_test.exs
index 2adfc57d..98aba0d8 100644
--- a/test/aggregate_test.exs
+++ b/test/aggregate_test.exs
@@ -2256,4 +2256,70 @@ defmodule AshSql.AggregateTest do
              "Calculation was not loaded when using page(count: true) with aggregates"
     end
   end
+
+  describe "join_filters in aggregate calculations" do
+    test "Ash.Filter structs in join_filters are properly converted to Ecto expressions" do
+      # This test reproduces the bug where Ash.Filter structs in join_filters
+      # are not properly converted to Ecto dynamic expressions, causing:
+      #   ** (Ecto.Query.CastError) value `#Ash.Filter<...>` in `where` cannot be cast to type :boolean
+      #
+      # The root cause is in ash_sql/lib/expr.ex - when a BooleanExpression contains
+      # an Ash.Filter struct as an operand, the private do_dynamic_expr/default_dynamic_expr
+      # functions don't have a clause to handle it, so the Ash.Filter is passed directly
+      # to Ecto instead of being converted to a dynamic expression.
+      #
+      # The bug triggers when authorization policies create Ash.Filter structs that get
+      # combined with join_filter expressions in BooleanExpressions.
+
+      # Set up authorization chain: User -> Organization -> Post -> Comment
+      org =
+        Organization
+        |> Ash.Changeset.for_create(:create, %{name: "Test Org"})
+        |> Ash.create!()
+
+      user =
+        User
+        |> Ash.Changeset.for_create(:create, %{})
+        |> Ash.Changeset.manage_relationship(:organization, org, type: :append_and_remove)
+        |> Ash.create!()
+
+      author =
+        Author
+        |> Ash.Changeset.for_create(:create, %{first_name: "Test", last_name: "Author"})
+        |> Ash.create!()
+
+      post =
+        Post
+        |> Ash.Changeset.for_create(:create, %{title: "test"})
+        |> Ash.Changeset.manage_relationship(:organization, org, type: :append_and_remove)
+        |> Ash.Changeset.manage_relationship(:author, author, type: :append_and_remove)
+        |> Ash.create!()
+
+      comment =
+        Comment
+        |> Ash.Changeset.for_create(:create, %{title: "comment", likes: 5})
+        |> Ash.Changeset.manage_relationship(:post, post, type: :append_and_remove)
+        |> Ash.Changeset.manage_relationship(:author, author, type: :append_and_remove)
+        |> Ash.create!()
+
+      Rating
+      |> Ash.Changeset.for_create(:create, %{score: 10, resource_id: comment.id})
+      |> Ash.Changeset.set_context(%{data_layer: %{table: "comment_ratings"}})
+      |> Ash.create!()
+
+      # This triggers the bug - loading a calculation that uses join_filters with actor reference.
+      # The join_filter `expr(author_id == ^actor(:id))` gets resolved to an Ash.Filter struct
+      # which is then combined with authorization policy filters in a BooleanExpression.
+      assert {:ok, [loaded_post]} =
+               Post
+               |> Ash.Query.filter(id == ^post.id)
+               |> Ash.Query.load(:max_rating_with_join_filter)
+               |> Ash.read(actor: user)
+
+      # The rating won't match because the comment's author_id doesn't match user.id,
+      # but the important thing is the query executes without CastError
+      assert is_nil(loaded_post.max_rating_with_join_filter) or
+               loaded_post.max_rating_with_join_filter == 10
+    end
+  end
 end
diff --git a/test/support/resources/post.ex b/test/support/resources/post.ex
index 4f6c1daa..145858b7 100644
--- a/test/support/resources/post.ex
+++ b/test/support/resources/post.ex
@@ -622,6 +622,7 @@ defmodule AshPostgres.Test.Post do
     attribute :keyword_map, :keyword do
       public?(true)
       allow_nil?(true)
+
       constraints(
         fields: [
           display_template: [
@@ -630,6 +631,7 @@ defmodule AshPostgres.Test.Post do
         ]
       )
     end
+
     attribute(:list_of_stuff, {:array, :map}, public?: true)
     attribute(:uniq_one, :string, public?: true)
     attribute(:uniq_two, :string, public?: true)
@@ -1211,6 +1213,19 @@ defmodule AshPostgres.Test.Post do
 
     calculate(:past_datetime1?, :boolean, expr(now() > datetime))
     calculate(:past_datetime2?, :boolean, expr(datetime <= now()))
+
+    # Test case for join_filters bug where Ash.Filter structs are not converted to Ecto expressions
+    calculate(
+      :max_rating_with_join_filter,
+      :integer,
+      expr(
+        max([:comments, :ratings],
+          query: [filter: expr(score > 0)],
+          field: :score,
+          join_filters: %{comments: expr(author_id == ^actor(:id))}
+        )
+      )
+    )
   end
 
   aggregates do