“Under the table” sort of implies you won’t be reporting it. They know about 1099 type stuff, as well as getting reports from your brokerage and everywhere else.
90% of Americans the only real question is if you updated your w-4 or not to reflect recent changes as well as relevant deductions which probably should just go away. (I mean, seriously. I drive to work just factor in the average and call it good- don’t make me track mileage.)