What to do if you can't pay your taxes when due...
File your tax return on time if at all possible. Pay as much of the tax bill as you can at that time.
Contact the IRS
Call the IRS at 1-800-829-1040 to discuss payment options. Do not proscrastinate dealing with the problem. Contacting the IRS quickly may help reduce your penalites.
Consider the payment options available
The IRS may be able to offer you options. This may include a full-payment agreement, an installment agreement, an offer in compromise, or a temporary collection delay.