The need to file is determined by Citizenship, Filing Status, Income and Age.
Living and working abroad does not mean you don’t have to file, even if your income is below the exclusion level. You must file in order to claim the exclusion.
The US considers everything received as taxable income. This includes base salary and all allowances and benefits, even if not received directly by you. In addition to the foreign earned income exclusion there may be other deductions and credits available to reduce taxable income or tax liability.
If you are not a US citizen or Green Card Holder, you may need to file as a Non-Resident to disclose income received from US sources during the year.