You can still file your 2016 taxes. If you receive a refund this year, your refund amount will go towards the 2015 amount owed. Or you can contact the IRS to make payment arrangements or make arrangements online.
To make arrangements online, click the link below:
https://www.irs.gov/payments
You may also request an installment agreement by calling the toll-free number on your bill, or if you don't have a bill, call us at 800-829-1040.