I allowed my boyfriend to use my bank account to receive his tax refund for 2020. How do I keep him from doing this again when he files for 2021

[VolvoGirl]

Actually the bank should reject the deposit if his name is not on the account.  Check with your bank.   Did you get his refund yet?  The bank should send it back to the IRS and the IRS will then mail a check to the address on the tax return.