On a personal level, I had forgotten to make a final payment for my 2020 return. I received a notice in August 2021 and immediately paid online. I, and my husband, have since been barraged with collection notices. Even after sending a timely response in October, we then received a notice to garnish our SS for payment (2 copies to each of us!).i've tried calling too many times to count and decided to sit still.  Fast forward to March 2022 the notices stopped and we finally got a letter saying ..... we're looking at this give us another 60 days.  Word is they are seriously understaffed so just hang tight and let them catch up with what they have rather than sending a barrage of more information or hounding Taxpayer Advocate offices which is also understaffed.  I say this as a former Revenue Agent, myself.