We have a Vendor Bill dated Apr 2023. March to May 2023 tax periods are already locked. June 2023 and the subsequent tax periods are still open. Why are we getting this error below when approving the Vendor Bill even if we have an open tax period? I assumed it would go to Jun 2023 tax period but no. Updated Transaction Failure: No valid, open, tax period for date - null

You have amortization schedule on your line ? Perhaps you can re open the April period

No, there's no amortization schedule. We can't reopen the period anymore as a company policy. It was working fine before.