If you mail your payment and it is postmarked by the due date, the date of the US postmark is considered the date of payment. If your payments are late or you did not pay enough, you may be charged a penalty for underpaying your tax.
We also suggest mailing payments by certified mail. This enables tracking the payment and also proof that your payment was sent. This is needed in case the IRS fails to receive or issue credit for payment received. We will mail these payments certified on behalf of our clients at no extra charge; just drop off your check and payment voucher!