After you file

Thanks so much for your reply.  Do you mind clarifying:  Does that mean I will not need to write a check prior to December 31 2021 for half the amount being deferred, simply roll it into my tax return for 2021 that I'll prepare in early 2022?    And, the same procedure for 2022, including in a return for that year that I'll prepare in early 2023?  And, my understanding is that this is interest free-correct?  Again, your help is very much appreciated.