How many years of late US tax returns do I need to file?

The number of years of US expat taxes you need to file will depend on your situation. Typically, three to six years will be sufficient for the IRS to consider you caught up. If you are trying to sponsor a spouse for US citizenship, up to eight years may be required in order to prove your ability to support your spouse as a US citizen. If you need to get caught up to prove financial merit (for instance, if you are applying for a loan), three years is generally enough. That said, every situation is different; you should discuss your options with an expat tax expert to make sure you file the correct number of returns.