SA109 form Box 16 - Personnal allowances

I am a Non-Resident UK Citizen . I have had my Tax calculation back and have noticed that my Personal Allowance (£12570) has not been taken into consideration. Question 1 :- Could this be because i did not tick Box 16 of the SA109 Form i.e. ( if you are entitled to claim personal allowances as a non-resident ......) If i click this box does this then mean that my personal allowance is then applied to tax calculation. Question 2 :- Do I need to fill out an R43 form ( Claim to personal allowances....... not resident in the UK), or is Box 16 of Question 1 is enough. Thanks.....

Hi
Yes.
You need to claim the allowances at either box 15 or 16 on the SA109.
The R43 is not required.
Thankyou.

Thank you HMRC Admin 10 for the quick reply. That explains everything here..... I admit it is my error by not ticking these boxes (I had just assumed that it would be inferred that I am UK Citizen). How can I correct this for the last 2 years Tax returns ? (i.e. i did not tick box 16 for both years 2020 and 2021). Are there Forms I have to fill in? if so which ?..... Or do I have to make phone call.... if so which number/department do I have to deal with (not forgetting I live outside of the UK). Any information will be gladly appreciated.

Hi,

To claim the personal allowance for the 2020 and 2021 tax years, please write to HMRC at the address shown below.                              

Claim personal allowances and tax refunds if you live abroad                                                                     

HM Revenue & Customs
BX9 1AS
United Kingdom

Thank you.