Carry forward calculators going back more than 3 years?

stoozie1

This is probably really obvious, but why does (for e.g) the HL carry forward calculator require 15/16 figures to calculate 19/20 total allowance?

I thought the years to carry forward from would be 18/19, 17/18 and 16/17.

beamyup

Have a look at the PDF that they supply

https://www.hl.co.uk/__data/assets/pdf_file/0005/5844632/Annual-Allowance-and-Carry-Forward-Factsheet.pdf

in there they state
" If total contributions exceeded your annual allowance in any of the
last three tax years you cannot carry forward any allowance from
that year. The excess may also use up unused annual allowance
from an earlier year. This can mean you may have to look back
more than three years to work out how much of your allowance
has been used. E.g. if you have exceeded £40,000 in 2018/19,
this might be supported by unused allowance from as early as
2015/16, leaving unused allowance from 2016"