WBTPA

We have an audited plan that transferred to a PEP last year. The assets transferred May 31, 2023, the PEP considered it a transfer of assets not a plan termination. The auditors are doing a combined audit of 2022 and the for the short plan year period of 1/1/2023-5/31/2023 (when the assets transferred). My question is... what is the due date of the Form 5500 for the short 2023 plan year? Thank you,