US citizens living abroad are subject to the same tax laws as those living in the US. This means that if you are a US citizen, you are required to file US taxes on your worldwide income, regardless of where you live. However, there are some exceptions and special rules that apply to US citizens living abroad.

First, it's important to determine your tax residency status. You may be considered a US tax resident even if you live abroad if you meet certain criteria, such as spending a certain number of days in the US or having a US home. If you are a US tax resident, you must file a US tax return every year, even if you live abroad.

If you are not a US tax resident, you may still be required to file a US tax return if you have US source income, such as rental income from a US property or income from a US business. You may also be required to file a US tax return if you have foreign financial assets that exceed certain thresholds.

One of the most important forms for US citizens living abroad is the Foreign Bank Account Report (FBAR). If you have foreign financial accounts with a total value of $10,000 or more at any point during the year, you must file an FBAR. Failure to file an FBAR can result in significant penalties.

Another form that may be required for US citizens living abroad is the Foreign Account Tax Compliance Act (FATCA) form. This form is required if you have foreign financial assets that exceed certain thresholds and provides information to the IRS about your foreign financial accounts.

It's important to note that the US has tax treaties with many countries that may affect your tax liability. These treaties can help to avoid double taxation and may provide additional tax benefits for US citizens living abroad.

In summary, US citizens living abroad are still required to file US taxes on their worldwide income. If you are a US tax resident, you must file a US tax return every year. If you are not a US tax resident, you may still be required to file a US tax return if you have US source income or foreign financial assets that exceed certain thresholds. Be sure to consult with a tax professional to ensure compliance with US tax laws and any applicable tax treaties.