A client came to us with some prof. subs from prior years, so we completed P87s going back to 09/10 and sent them in in March 14. Calcs came through and they have ignored the 09/10 claim. After speaking to them they said the client was in SA in 09/10 (which we weren't aware of) and so the P97 was inappropriate and thus ignored!
When I've done prior year adjustments for SA clients before I have (rightly or wrongly!) usually just sent a letter saying 'box x should be y' broken down by year to HMRC and they have always processed it without fuss (well, for HMRC).
So why would an HMRC form giving the same info be inappropriate?
Or am I being naive and have been doing it wrong all these years (and HMRC have just been kind)?