Cross Border and Split Year Treatment

[CMCW92]

Can anyone assist with my partner's situation.

1. Worked and lived in NI until May 2023.
2. Worked in NI and Lived in ROI from May 2023 to Nov 2023.
3. Worked and lived in ROI from Nov 2023 till present.

When moving, they didn't declare anything apart from the new Job on revenue, so there was no tax due on the ROI Nov and Dec pay.
However, once declaring the UK pay, I assume they will have to pay Nov and Dec tax then, but it's the declaring part that's confusing.

Do they declare all income and tax paid in UK from Jan 2023 to Nov 2023?

Trying to find where to do that properly on the PAYE tax return is quite confusing.