If you fail to file a tax return in any year you have sufficient income, the IRS can impose interest charges on all unpaid tax balances plus various penalties. Separate penalties exist for both your failure to pay tax and for not filing a tax return on time, or not filing it at all. American expatriates also run the risk of losing special tax benefits such as the foreign earned income exclusion if the IRS contacts you before you file the delinquent returns. Plus, you may run into additional problems when you return to the U.S.