File your tax return even if you can’t pay. If you can’t file, request an extension and pay what you think you owe—or at least part of it.
Here is what the IRS says:
Taxpayers who owe taxes and don’t file their tax return by the deadline may face interest on the unpaid taxes and a failure-to-file penalty. Interest and penalties add to the total amount a taxpayer owes. Filing by the deadline allows taxpayers to avoid the failure-to-file penalty, even if they can’t pay all or some of their taxes by the deadline. Taxpayers who can’t file their return by the deadline can request an extension of time to file. However, an extension of time to file is not an extension of time to pay.