The IRS provided deadlines for filing 2015 income tax returns in Revenue Ruling 2015-13, taking into account the fact that the IRS no longer requires income tax returns to be filed with the Service Center in Andover, Massachusetts.

The issue arises due to the fact that April 15 in 2016 will fall on the third Friday in April. This sets in motion a series of issues, since the District of Columbia will recognize Emancipation Day (normally a formal holiday in the District celebrated on April 16) on April 15 since the 16th falls on a Saturday.

This will push the “normal” filing date to April 18 for both the 2015 Form 1040 and the first estimated tax payments for 2016, since federal law generally provides that official public holidays recognized in the District of Columbia are treated as holidays for federal tax purposes, pushing the filing date across the country to the first regular business day following that holiday.

However Monday, April 18th is set as Patriot’s Day in the states of Massachusetts and Maine—that holiday is set as falling on the third Monday in April, which will be April 18th this year (the date becomes the default filing date due to Emancipation Day falling on April 15). Though taxpayers living those states no longer are filing returns with a Service Center located in a state that recognizes the holiday, the IRS has held that federal law allows taxpayers in those states to file their returns by hand with the local IRS offices. As those offices will be closed in recognition of the local holiday, the taxpayers in those states will have until April 19th to timely file their federal returns.

However since those taxpayers are required to file their estimated tax vouchers with a depository in Hartford, Connecticut, a state that will not be treating April 18th as a holiday, the holiday will not push back the date on which they must file their first estimated tax payment for 2016—that payment will still be due to be filed on or before April 18th, despite the fact their 1040 can be timely filed a day later.