You can see what account info you entered on your tax return by looking at the bottom of form 1040 near the signature line.  Direct Deposit information will also be shown near the top of the filing instructions sheet.

The previous answer is correct.  You can also go thru old Turbo Tax year software and look it up under e-file.  If your question pertains to the Stimulus check deposit who know how IRS figured it out.  I have had same checking account and filed efile taxes for over 10 years and IRS didn't send a stimulus check automatically like they said they would.  I had to apply on the IRS website, and they ended up sending a debit card to me.  Go figure, after my account has been on file for all these years.  Luckily I could transfer they funds from the debit card to my account, after establishing an account with Eipcard (the bank the IRS put the money into)  The whole event was crazy and not as advertised thru all the media outlets.