Tax Returns and Foreign Bank Account Report

Information listed here pertains to the USA.
Persons of other nationalities refer to your own government agencies for requirements.

Filing Your Taxes 

If you are a U.S. citizen or resident alien residing overseas, or are in the military on duty outside the U.S., on the regular due date of your return, you are allowed an automatic 2-month extension to file your return and pay any amount due without requesting an extension (June 15). source

Report of Foreign Bank and Financial Accounts (FBAR)

U.S citizens, resident aliens, and certain non-resident aliens that have an interest in specified foreign financial assets totaling more than $10,000 must report these accounts yearly source

FBAR filing is done online and can be completed in less than 10 to 15 minutes source

Additional reading

When Does a Senior Citizen on Social Security Stop Filing Taxes?

Minimum Income Requirements to File a Federal Income Tax Return