Extension impact calculator

Step 1 captures the tax year and the balance you believe you owe. The calculator uses this estimate as the base for penalty and interest projections. It also asks how much you paid by the deadline so it can identify the remaining balance that may accrue penalties.

Step 2 records payment and filing timing. You can enter payment and filing dates or the number of days late if you already know them. The extension toggle changes which filing deadline applies so the calculator can apply the right failure-to-file rules.

Step 3 applies IRS penalty rates and the annual interest rate you provide. The tool estimates failure-to-pay, failure-to-file, and interest based on the timing and remaining balance. It also shows a recommended minimum payment to reduce risk.

Step 4 summarizes the results and points to a next action. The summary highlights the remaining balance and reminds you that an extension is not extra time to pay. Missing inputs are flagged so you can refine the estimate if your payment details change.

Step 5 records the payment details you entered so you can revisit the estimate later. Extension scenarios often involve partial payments or staggered timing, and the tool keeps those details visible. That way, you can update the estimate as new payments are made without re-entering everything.