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How to File for the December 15 US Tax Extension in 2021

Expat Tax Blog | Tax Tips for US Americans Abroad

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How to File for the December 15 US Tax Extension

If you are an American living abroad and the thought of filing your US tax return for the October 15 deadline concerns you, you can take a deep breath. You have the potential to be qualified for extending your tax filing obligation to the December 15 deadline!

Necessary Tax Filing Obligation Information

Before we start explaining how to file for the December 15 US tax extension, we must share the standard US expat tax deadlines and extension dates.

As an American or Green Card Holder living abroad, you must report your worldwide income if your adjusted gross income is above the filing threshold.

Expats who need to file their US taxes receive an automatic 2-month extension to report their worldwide income. We made it easy to do this via our expat tax software. However, if you owe US federal or state taxes, you’ll need to file by the typical filing deadline of April 15.

Additionally, US expats could apply for a free tax extension, or write a letter to the IRS and mail it by post to request more time to do the tax work until October 15. However, you must fill out the free tax extension form through our software before the June 15 deadline.

Since we are passed filing for the October extension, you can still file an extension for the December 15 deadline. You can do this by filing Form 1040 with additional documents we’ll explain below.

Writing and Sending a Letter to the IRS

There is no way to send an online email or message to the IRS requesting an extension to file US taxes until the December 15 deadline. Instead, you’ll have to use the traditional route of writing and mailing a physical letter to the IRS. This process is according to the current regulations by the US Treasury.

Points to write in the letter:

  • Which tax return or documents and the year or tax period you need to get an extension for.
  • A reason why the IRS should grant you the time to extend your tax filing obligation to December 15 (and not October 15).

This reason could be that it takes extra time to collect expense and income documents to prepare your 2020 tax return. Especially since you live abroad as a US citizen, and communication and mailing delays could happen. Whatever is truthful and applies to your situation should work. It’s crucial you come off confident and as a conscientious taxpayer.

Example Letter for the IRS


“I, (full name), request an extension to file Form 1040 for the 2020 tax year until December 15, 2021. The reason is ______ . I sincerely hope I can have this extension.

Best regards,

(Your name)

Make a couple of copies of this letter to have on file!

Mailing Address of the IRS in the United States

Please send your letter in an internationally stamped envelope to

Department of the Treasury
Internal Revenue Service
Austin, TX 73301-0215

The above address would be the same as the IRS Service Center if you were to mail your US tax form. Additionally, we suggest you send your letter through a private delivery service like DHL or FedEx. Using these services allows you to receive the signature of proof that your letter arrived safely at the headquarters.

Send your Letter as Soon as Possible

With the current pandemic, and shipments of Stimulus checks getting delayed for Americans abroad, we suggest not to wait and submit your letter as soon as possible. Hence, it arrives at the IRS before the October 15 deadline. Yes, folks, you need to have your letter in on or before October 15 of this year.

Getting no IRS notice or confirmation from the IRS about your letter as a US citizen abroad is normal. You won’t hear whether your letter was processed and the extension accepted by the IRS. But you can have a representative sign that your letter has arrived at their office, as we explained above.

Start Filing for the December 15 Deadline

Despite not receiving a confirmation you are granted the December 15 extension, you should still go ahead, prepare and file your 2020 tax return.

Of course, you have us at MyExpatTaxes who can happily accept you and allow you to walk through our DIY expat tax software for as little as 149 Euro.

Otherwise, you can fill the tax documents manually through the following steps:

  1. Attach a copy of the letter you wrote to the IRS requesting an extension with your 2020 tax return. Write ‘’Taxpayer Abroad’’ on top of Form 1040.
  2. Mail it to the address above at your local post office.
  3. Congrats, you’re done!

We’re Here for You

Our growing, friendly, dedicated team of tax professionals are here to support you every step of the way. And if you’re not convinced of our software and service, take a look at our reviews on Facebook or hop into an American expat community to see what fellow Americans abroad say about us. Our US tax filing process is streamlined, simple, and affordable.

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