After you file

I also received a notice from the IRS that being that they were not able to provide me an economic impact payment before December 31, 2020 that I would need to claim as a recovery credit when I file for my 2020 refund. I also want to note that I’ve been receiving all future dated notices from the IRS, is that legal? For example, on January 11th I received a notice dated for January 18th