I received 1099-R form in 2020 and since IRS allowed to pay penalty in 3 installments, I paid my 1st penalty amount in 2021, Where do I put my 2nd installment detail.

You will report this in the Retirement Plans and Social Security section under Wages & Income.  However, the Form 8915-F has not been finalized by the IRS for including in a 2021 tax return so the questions are not being asked until the form is available.  There is no estimate from the IRS when this form will be available, but guessing sometime in March 2022.

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If you qualified for COVID-related tax treatment, there was no penalty.

Conversely, if you did not qualify, you were not allowed to divide any penalty into three installments.