We have a small number of transactions that slipped into the incorrect tax period, before the tax period was closed. So they are in the Dec 23 tax period and we need them in the Jan 24 tax period. I've checked and now the tax period and the accounting period for December are fully closed. If I edit or change the transaction, even adding a new line of data, doesn't force this into the Jan 24 tax period it just adds it to the closed Dec 23 tax period. Is the only way to remove the transactions and re-enter them? Or, is there another way I can trigger a change on the tax period. TIA

You'd have to re-open the period if you want to make a GL-impacting change to that period (change the period on a transaction).

The transaction are in Jan 24 period - which is open, and we want the Tax period to be Jan 24 which also is open. I've created a test transaction and everything is correct. The problem is to change the tax period from Dec 23 to Jan 24.

Thanks for the link, but perhaps I didn't explain correctly. The accounting period and tax period I want the transaction to be in are both open. The transaction currently has a/c period = Jan 24, tax period = Dec 23. Dec 23 tax period is closed. I want to edit the transaction and move the transaction so it is a/c period Jan 24, tax period Dec 24.

you'll need to reopen the tax period then if you want to edit

I've managed to sort it... I reopened Dec 23 tax period. Changed the dates in the transaction to Jan 24. Closed the tax period, and changed the dates back to Dec 23 and the tax period now shows Jan 24 as required. @James Morris thanks for your advice.