The US taxes its citizens on their worldwide income wherever they live. So as a US expat, your annual obligations go well beyond filing a tax return.
The two that matter most are FBAR and FATCA. Missing either one can bring penalties far larger than any tax owed, even when no extra tax is due.
We don't file these returns ourselves. We make sure every planning decision we make for you takes them into account, and we can refer you to US tax professionals who handle expat filings every day.

Yes. US citizens and green card holders file a federal return wherever they live. If you're abroad on the April deadline, you get an automatic extension to June 15 to file, but any tax due still accrues interest from April 15.
FBAR (FinCEN Form 114) is required if your non-US bank, brokerage and pension accounts together exceed $10,000 at any point in the year. It's filed online with FinCEN by April 15, with an automatic extension to October 15.
It reports foreign financial assets with your tax return. If you live abroad, the thresholds are $200,000 at year-end or $300,000 at any time if you're single, and $400,000 at year-end or $600,000 at any time if you're married filing jointly.
No. They don't go on either form. It's the accounts you hold in your new country that count, which is one more reason to keep your long-term retirement savings in the US.
Penalties for missed FBARs can run into thousands of dollars per account, even when no tax was owed. The IRS has streamlined procedures for catching up. Speak to a US tax professional before you file.