If you live outside the United States, you probably already know that you receive an automatic two-month extension to file your U.S. income tax return. That means the usual April 15 deadline moves to June 15 for many U.S. citizens and green card holders living abroad. So if that’s the case, you might reasonably wonder why your U.S. tax compliance professional keeps bringing up April 15. The short answer: the extension applies to filing your return, not to paying the tax.

Why It Matters

Even with a filing extension, many expats still face tax obligations on April 15. Misunderstanding this distinction can lead to unexpected interest charges. By reviewing income, foreign taxes, and investment activity early, expats can make informed payment decisions, reduce potential liabilities, and ensure a smoother tax filing process come June.

Filing vs. Paying: Two Different Deadlines

For U.S. expats, the automatic extension to June 15 applies to filing Form 1040 and related forms. However, the deadline to pay any tax owed generally remains April 15.

If tax is paid after April 15, the IRS may assess interest on the unpaid balance, even if the return itself is filed later under the expat extension.

Because of this distinction, your tax advisor is often trying to determine two things before April 15:

1. Whether you may owe tax for the prior year
2. Whether you should make an estimated payment for the current year

Why Expats Sometimes Owe U.S. Tax

Many expats assume that living in a higher-tax country means they will never owe U.S. tax. Often that is true. But not always.

The U.S. expat tax toolbox includes several provisions designed to prevent double taxation, such as:

• The Foreign Earned Income Exclusion
• The Foreign Tax Credit
• Tax treaties with certain countries

These provisions help reduce or eliminate U.S. tax in many situations. But they do not always perfectly align with the tax rules in your country of residence.

Take Switzerland as a simple illustration:

In Switzerland, capital gains on private movable assets such as stocks or ETFs are generally not taxed. Instead, Switzerland imposes a wealth tax on the value of your assets.

For U.S. tax purposes, however, capital gains are taxable. Because Switzerland typically does not impose an income tax on those gains, there is no foreign income tax available to claim as a credit against the U.S. tax on those gains.

The result can be unexpected U.S. tax liability even though your local tax system may treat the income differently.

Another Common Scenario

Another situation we see frequently involves the Foreign Earned Income Exclusion (FEIE).

If you live in a relatively lower-tax jurisdiction and your earned income exceeds the exclusion amount, your foreign tax may not fully offset the U.S. tax that would otherwise apply. In that case, there may still be a residual U.S. tax liability.

Why Your Advisor Wants Numbers Before April

Because of these differences between tax systems, your tax advisor is often trying to estimate your tax position before April 15, even if your return will ultimately be filed later.

Doing this allows us to:

• Determine whether a payment for the prior year should be made by April 15
• Consider whether a first-quarter estimated payment for the current year should also be made

Making timely payments helps reduce the risk of interest or estimated tax penalties later.

Even though U.S. expats typically receive an automatic extension to June 15 to file, April 15 still matters for tax payments. That’s why your tax professional may start asking questions about your income, investment activity, or foreign tax position well before the June filing deadline.