Behind my desk sits a file with completed documents. The client refuses to pick-up or file the forms with the IRS because she is short the amount due. Of course, you realize, she is only digging the hole deeper.
Friendly advice from your local accountant: Always file on time, even if you can't pay. Why? Because there are several IRS penalties in this world: penalties for not paying on time and penalties for not filing. The last penalty is a self-inflicted wound. File on time and set-up a payment plan, thereby forgoing the late filing penalty.
This is the easy way to reduce your tax burden. It is bad enough you have to pay taxes, why volunteer to pay extra.