I may need some help on how to word this question, but essentially I want to know what Toomes' cover was for his career.
Early in the film, we learn his latest construction gig has been taken over by The Department of Damage Control. We see this leads him to go into the illegal arms deal business for 8 years (until the film's present day). Obviously he isn't writing that on his W4.
Theoretically, he could continue what he was doing and get new gigs doing clean-up around the city; however, given that the average foreman salary is around $60,000, this seems unlikely to cover the large amounts of money coming in from the weapons sales. We also learn he lives in a fairly large (for NYC suburb standards) home, owns a fancy car, and puts his child into private school. This would be unusual for someone whose yearly income is in the under $100,000 range.
If his wife, Doris Toomes, was the main breadwinner for the family and the reason for having this plush life (which we do not learn at all in the film), it seems unlikely that Adrian would be so desperate as to do something illegal for his family to make money, since they wouldn't be in a terrible financial situation.
What was Adrian Toomes' job on a tax form?