1. If you select that you want to print and mail your returns, you can mail them at any convenient time. If you want to e-file, you must e-file the federal at the same time as the state, or you must e-file the federal first and wait for it to be accepted, before e-filing the state return. You can't e-file state first.
2. If you owe, you owed as of April 15, and the penalties and interest are piling up. If you think you need your state refund to pay your federal tax bill, you can do that by mail, but it may take longer, causing more penalties.
3. If you have an extension to file to October 15, then the penalty for late filing and late paying is about 1.25% per month of what you owe. But if you don't have an extension, the late filing penalty is 5% of what you owe per month, plus 0.75% interest.
4. Your best course usually is to e-file both returns now, but if you owe, indicate you will "pay by check." Turbotax will not include a bank draft on your account. Then, go to www.irs.gov/payments and make a voluntary payment of as much as you can afford. Then pay the rest as soon as you can. Expect to receive a bill for penalties and interest.
5. When you get your bill for the penalty, penalties can sometimes be waived for good cause (if you have a good cause). Interest can't be waived, but if your application to waive the penalty is granted, the interest will be recalculate to not include the penalty in the interest charge.
