I invite your attention to IRS Newswire IR-2017-59, dated March 14, 2017, that outlines in detail the various payment options available to all taxpayers for the payment of their federal income taxes.

If your clients' income tax withholdings are not sufficient to cover their liabilities, you should have them make quarterly estimated tax payments using Form 1040-ES or indicating such payments using one of the methods Thomas has indicated below, which can also be found here: www.irs.gov/payments. If your clients owe balances that they cannot pay all at once and do not expect to be able to pay off over the next 4 to 6 months, then they may want to consider a payment plan or installment agreement with the IRS. However, interest and penalties will continue to accrue until the full amount is paid off. Please see: www.irs.gov/individuals/payment-plans-installment-agreements