you can shred them for years prior to 2017. The Social Security Adm has copies if you ever need them but there's a fee. for 2017-2019. if you're due a refund you can still claim them by filing but you would either need TT desktop software for each year or download the forms from the IRS website and prepare your returns manually. for years prior to 2017, any refunds due to you have been forfeited because you did not timely file.
