Filling in N.I gaps when I lived abroad

pinnks

If you want to pay voluntary NI in relation to periods abroad you must send form CF83 to HMRC.  If they receive that before 6 April 2025, they have said many times on public forums that you will not be disadvantaged by their delays, i.e. the deadline for you is essentially extended until they deal with your form and give you a period within which you would then have to pay.

If you worked in the UK until immediately before you left then the door to pay at Class 2, rather than Class 3 is open.  For any week you were then working abroad you can pay at Class 2.  For weeks you were not working it would be Class 3, so you can end up with a full year Class 2, or Class 3 or a mix of both.

Your online NI record will only ever show the Class 3 cost for paying voluntary NI, even if you ultimately qualify to pay Class 2.