US Citizens plus the Green card holders need to file tax returns in the US even when they have moved overseas. The foreign income and accounts need to be declared in the country you are a citizen of, which in this case is the US. The IRS has a streamlined filing compliance procedure to help the citizens file their US tax returns or amend returns while declaring their foreign income and accounts.
The streamlined process is available for the US citizens residing in the US and the ones residing overseas. There are two parts- one is called the Streamlined Foreign Offshore Procedures for those living outside US and the Streamlined Domestic Offshore Procedures for the ones living in the US. The streamlined foreign offshore procedure consists of 3 parts namely US tax returns, Disclosure document to explain why you have not been filing, and Foreign bank account reporting.
The last 3 overdue tax returns need to be filed at the earliest and the IRS demands answers to why it has been due until now. IRS waives all the returns that have not been filed before them. The income will be reported under ‘worldwide income’ even when it has already been taxed and declared in the overseas.
People mistakenly do not file the returns thinking that if there is the foreign earned income exclusion ($107,600 for 2020), then they do not need to show the income in the home ground. But that is not the case. The filing criteria are the same whether you are living in the US or not. You need to claim the foreign earned income exclusion and declare worldwide income too.