Skinny Ant

I haven't contributed to a pension for 10 years. I want to make the most of my allowances and carry forwards before 5 April 2024. No financial website is explicit on this. Does 3 years carried forward include the current year or is it actually 4 years? Although a higher rate tax payer, I assume I still contribute at net of 20% rate and claim back additional relief in self assessment? My understanding is I am max I can contribute is £17,600 this year, made up of 80%of £22k allowances over 4 years : 23/24 = £10k max taper 22/23 = £4k max taper (c/fwd year 1) 21/22 = £4k max taper (c/fwd year 2) 20/21 =£4k max taper (c/fwd year 3) I can then still claim additional tax back in my self assessment but not clear if that is just for year 22/23 or if I can claim additional tax back for the 3 c/fwd years too? Would appreciate confirmation if my logic is correct as don't want to over contribute and be hit with a tax charge. thanks