diff --git a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
index 5a7cdeddd2a9257f264910e9665ecdda1244315d..2f218ea465caea3c7babb6a9d3f18eddfcc450d8 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
@@ -824,23 +824,27 @@ let cost_check_proof_start_stop =
 
 (* TODO: https://gitlab.com/tezos/tezos/-/issues/2926
    This function is incomplete and needs to account for additional gas. *)
-let cost_play ~number_of_sections _game refutation =
+let cost_play ~number_of_sections game refutation =
   let tick_size = Sc_rollup_tick_repr.size_in_bytes refutation.choice in
   let cost_find_tick =
     Sc_rollup_costs.cost_find_tick ~number_of_sections ~tick_size
   in
   let cost_refutation =
-    match refutation.step with
-    | Dissection states ->
+    match (refutation.step, game.game_state) with
+    | Dissection states, Dissecting _ ->
         let number_of_states = List.length states in
         let hash_size = State_hash.size in
         Sc_rollup_costs.cost_check_dissection
           ~number_of_states
           ~tick_size
           ~hash_size
-    | Proof _proof -> cost_check_proof_start_stop
+    | Proof proof, Dissecting _ ->
+        let cost_valid =
+          Sc_rollup_proof_repr.cost_valid proof proof.input_proof
+        in
+        Gas_limit_repr.(cost_valid +@ cost_check_proof_start_stop)
+    | _ -> Gas_limit_repr.free
   in
-
   Gas_limit_repr.(cost_find_tick +@ cost_refutation)
 
 let play dal_parameters ~dal_attestation_lag ~stakers metadata game refutation =
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.ml b/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.ml
index 4dd15a754a49c536642190bae60b16c62743b04e..287704dd1447c3aac01276e0551d0117606297f9 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.ml
@@ -347,6 +347,43 @@ let valid ~metadata snapshot commit_level dal_snapshot dal_parameters
   in
   return (input, input_requested)
 
+(* FIXME: https://gitlab.com/tezos/tezos/-/issues/3290
+   This needs to implemented. *)
+let cost_check_inbox_proof _inbox_proof = Gas_limit_repr.free
+
+(* FIXME: https://gitlab.com/tezos/tezos/-/issues/3290
+   This needs to implemented. *)
+let cost_verify_dal_proof _proof = Gas_limit_repr.free
+
+(* FIXME: https://gitlab.com/tezos/tezos/-/issues/3290
+   This needs to implemented. *)
+let cost_verify_proof _proof = Gas_limit_repr.free
+
+let cost_valid_input_proof input_proof_opt =
+  match input_proof_opt with
+  | Some (Inbox_proof {level = _; message_counter = _; proof}) ->
+      cost_check_inbox_proof proof
+  | Some First_inbox_message -> Gas_limit_repr.free
+  | Some (Reveal_proof (Raw_data_proof _)) -> Gas_limit_repr.free
+  | Some (Reveal_proof Metadata_proof) -> Gas_limit_repr.free
+  | Some (Reveal_proof (Dal_page_proof {proof; page_id = _})) ->
+      cost_verify_dal_proof proof
+  | None -> Gas_limit_repr.free
+
+(* The cost is calculated by mirroring the structure of [valid]. *)
+let cost_valid proof input_proof_opt =
+  let (module P) = Sc_rollups.wrapped_proof_module proof.pvm_step in
+  let cost_valid_input_proof = cost_valid_input_proof input_proof_opt in
+  let cost_verify_proof = cost_verify_proof P.proof in
+  (* FIXME: https://gitlab.com/tezos/tezos/-/issues/3290
+     Here we also need to account for work involved in validating input proof
+     and input request. In particular hashing reveal hash data. However we
+     need to know the input proof here which we do not have access to.
+     Possible solution: split [valid] in two parts. *)
+  let cost_valid_input = Gas_limit_repr.free in
+  Gas_limit_repr.(
+    cost_valid_input_proof +@ cost_valid_input +@ cost_verify_proof)
+
 module type PVM_with_context_and_state = sig
   include Sc_rollups.PVM.S
 
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.mli b/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.mli
index 652b28109f4e916a682f42af61c897f6d53b747f..e11386e993f4183970df30c615d1a20785226c77 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.mli
+++ b/src/proto_alpha/lib_protocol/sc_rollup_proof_repr.mli
@@ -146,6 +146,10 @@ val valid :
   (Sc_rollup_PVM_sig.input option * Sc_rollup_PVM_sig.input_request) tzresult
   Lwt.t
 
+(** [cost_valid history_proof level ~pvm_name proof inbox_proof]
+    returns the cost of refutation proof validation. *)
+val cost_valid : t -> input_proof option -> Gas_limit_repr.cost
+
 module type PVM_with_context_and_state = sig
   include Sc_rollups.PVM.S