Important tax information letter from irs

there could be many things. we can't see it. so if you want help you'll have to tell us what it says leaving out personal info.

“Important tax information “ was noted in upper right hand corner of envelope. Can only see mail envelopes online as on vacation for a month. Was wondering what it could be for?

No way anyone could tell you for sure..

IF you have children, and received advance child tax credits....could just be the letter specifying how many $$ they sent you during 2021, so that you can enter the proper amount in your tax return.  (some folks are terrible at keeping track)   .   But other than that, could be most anything.