HSA Contribution

I self contribute to my HSA (retired) and got Medicare at 65 in August.  I found I could contribute another $1,400 to the HSA.  I met all other high deductable insurance requirements for HSA eligibility in 2020.  Can I contribute the additional $1.4K in 2021 for my 2020 taxes, similar to the ability that is given for IRA's?   Thanks.