Applying 2020 refund to 2Q21 estimated taxes

[barrettsteele]

I've filed an extension and now am ready to file my 2020 tax return.  I am owed a refund for both Federal and State and would like to apply those to my 2Q21 estimated tax payments.  Will it automatically be applied to that payment, even if the refund is processed after the 6/15/21 deadline (but the return is filed before 6/15)?  I don't want to be penalized for underpayment if they don't give credit on the deadline date.

Does anyone have experience with how this works?

[DoninGA]

To add, change or delete a current year federal tax refund to next year's taxes before you file your tax return -

• Click on Federal Taxes (Personal using Home and Business)
• Click on Other Tax Situations
• Under Additional Tax Payments
• On Apply Refund to Next Year, click on the start or update button

Or enter apply federal refund to next year in the Search box located in the upper right of the program screen. Click on Jump to apply federal refund to next year

The amount applied to next years taxes will be shown on Form 1040 Line 36

There will be a similar option in the state program you are using.

[barrettsteele]

Thanks for this explanation, but what I'm really trying to understand is when the refund will be counted toward 2021 taxes (which Quarterly payment).  I understand if you elect this as you described and file before the April 15 deadline, it is credited to the 1Q payment.  But we're way past that date now.  So, in situations where the person has filed an extension and elects to have a refund credited to the next year's payment, for which quarterly estimated payment does that refund apply?