Form 4868 Extension - Safe Harbor & Penalties
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Safe Harbor Payment

To reduce or avoid penalties, pay the following by April 15th:

  • 90% of your current year tax, or
  • 100% of last year’s tax (110% if your prior-year AGI amount was greater than $150,000; $75,000 if MFS)

Underpayment Penalty & Interest

Paying the safe harbor amount helps reduce penalties, but interest may still apply on any unpaid balance. See IRS Topic 306 for details about estimated tax/underpayment penalties.

  • Failure to pay penalty: 0.5% per month on unpaid tax (up to 25%)
  • Interest: Accrues from the original due date until paid (rate set quarterly)

Tax Calculator

Use our Income Tax Calculator to estimate your tax liability. This will help you determine how much you may owe, or if you can expect a refund. If you expect to owe, pay that amount when filing your extension. An extension gives you more time to file your return, not to pay.

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