You can go here https://turbotax.intuit.com/irs-tax-extensions/ to file a federal extension for your 2016 return. Keep in mind, filing an extension gives you until October 16 to file, but it doesn't give you until October to pay your taxes, if you owe. Those are still due by midnight, April 18.
Do I need to file an extension if I'm getting a refund?
https://ttlc.intuit.com/replies/3931358
And you can find details here below for how to file an extension for your state.
How do I file an extension for my state in Easy Extension?
