Do I have to file for tax if I use Acorns?

Sure, you may owe taxes on any dividends earned.

Dividends are companies' way of thanking investors for investing with them- they get paid simply by holding equity in that company at some point during the period when those dividends were being issued or reinvested back into its fund Acorns automatically reinvests these funds but just make sure not to forget about how much tax will be due once I receive my annual report!