I deferred some taxes (social security I think?) to be paid at the end of the year. Where can I find how much I deferred and who do I pay -- the IRS or Social Security?

[415california]

For 2020 self-employed were allowed to defer some of their tax liability -- some to be paid at the end of this year, and the rest at the end of next year.

[MaryK4]

You can find the amount on Schedule 3 Line 12e.  You must repay one half before December 31, 2021 and one-half before December 31, 2022.