Can you estimate a tax rebate?

Not_Angela_Rippon

HMRC wrongly gave me a Tax code this year of 803L and have now corrected this after I contacted them to 1060L. They said any change will be reflected in my pay but wasn't sure how easy it would be to estimate how much tax I have overpaid this year.

CLAPTON

if you had 803L from april to september i.e. 8 months

then you paid too much tax by (10600-8030) x 8/12 x tax rate

so that is 1,713 x 20% if a standard rate payer = £342