The requirements for filing the FBAR and Form 8938 are based on your foreign assets, not foreign earnings. You have to file an FBAR if you had a foreign account with a value of more than $10,000 at any time during the year. It doesn't matter where the money came from. So if you put $50,000 in a foreign account you definitely do have to file an FBAR.
You didn't give enough details to determine whether you would have to file Form 8938. If you are a U.S. citizen or resident alien, you live in the United States, and you are not married, you have to file Form 8938 if the value of your account is more than $50,000 on the last day of the year. So if you put in $50,000 and it doesn't grow at all, you would just squeak under the filing requirement. But if the account increases by just $1 you have to file.
Go to the following pages on the IRS web site for more details of the filing requirements, including the Form 8938 requirements for other situations.
Report of Foreign Bank and Financial Accounts (FBAR)
Do I need to file Form 8938, “Statement of Specified Foreign Financial Assets”?
This is not a complete discussion of the rules for filing these forms, and we do not know all the details of your situation. The rules are complex, and the penalties for not filing a required form are significant, so you might want to seek professional advice.
