Millions of taxpayers ask for an extra six months to file their taxes, according to statistics provided by the Internal Revenue Service. These taxpayers should have paid the tax they owed by the April deadline, but those who requested an extension should mark Monday, Oct. 16 as the extension deadline for 2017. While the deadline normally falls on Oct. 15, that date falls on a Sunday this year so the due date is moved to the next business day.

Here are IRS reminders for taxpayers who have not yet filed:

Try IRS Free File or e-file. Taxpayers can e-file their tax return for free through IRS Free File. The program is available on IRS.gov through Oct. 16. IRS e-file is easy, safe and the most accurate way to file your taxes.

File by Oct. 16. Taxpayers with extensions should file their tax returns by Oct. 16. If they owe, they should pay as much as possible to reduce interest and penalties. IRS Direct Pay allows individuals to securely pay from their checking or savings accounts. These taxpayers can consider an installment agreement, which allows them to pay over time.

More Time for the Military. Military members and those serving in a combat zone generally get more time to file. If this applies to you, you typically have until at least 180 days after you leave the combat zone to both file returns and pay any taxes due.

More Time in Disaster Areas. People who have an extension and live or work in a disaster area often have more time to file. The disaster relief page on IRS.gov has more information.

Use Direct Deposit. The fastest way for taxpayers to get their refund is to combine direct deposit and e-file.

Use IRS Online Payment Options. Taxpayers who find they still owe taxes can pay them with IRS Direct Pay. It’s the simple, quick and free way to pay from a checking or savings account. For other payment options, taxpayers can click on the “Payments” tab on the IRS.gov home page.

Keep a Copy of Tax Return. Taxpayers should keep a copy of their tax return and all supporting documents for at least three years. Among other things, this will make filing next year’s return easier. When a taxpayer e-files their 2017 return, for example, they will often need the adjusted gross income amount from their 2016 return.