How do I determine what date my taxes are considered paid? is it the date I mail a check to the IRS? if I pay using EFTPS is it the date that I submit the payment?

[kmrentfrow]

Estimated taxes were underpaid, documents required to complete the tax return are not available and might not be available for a long time. I want to pay based on documents I do have and my best guess for the rest to reduce the penalty for underpaid estimated taxes so I will file for an extension and make a payment. When get all of the documentation and complete my taxes, what date do I use as  the date that the payment was made when I calculate the penalty?

[Leonard · Accepted solution]

Generally, the date of the  US postmark stamped on a return, claim, statement, document, or payment that is mailed shall be deemed to be the date of delivery or the date of payment.

For EFTPS payments the payment is the date that you submit the payment.

[TaxHacks]

I think it is the date that the payment is dated. If you enter the payment on April 15, it is not going to be dated April 15. You cannot enter a payment into EFTPS, I think, for the same date as the payment date.