I recently left a job in the USA year. This year I will have to file a tax return due to the income I earned in the USA. However, if I leave my 401k and HSA untouched in the USA, will I be obliged to file a tax return year after year simply due to their existence? Or would I only be obliged when I begin withdrawing money? Thanks.
Having 401k or HSA is not income and doesn't trigger filing requirements. Withdrawing from 401k or HSA does. Also, in some States, HSA gains are taxed as investment income, so if you have gains in an HSA and you're a resident of such a State - you'll need to file a State tax return and pay taxes on the gains.