This Past Year An An Employer Held Out Taxes On My Check But Never Actually Paid Them In. (thousands!!) Don't Know Who To Report This To!

Last year my boyfriend worked for a small company (HVAC LLC company with like 2-3 employees) for several months. He was making 30/hr and working 60-80 hr weeks so there is a good amount of money involved, an average weeks check was between $1800-3000. My boyfriend WAS A W-2 employee and all standard taxes were withheld. The first couple of checks were paper checks, afterwards he started making up reasons why he had to pay in cash, (he was still holding taxes out even when paying cash, this was NOT under the table) After that we went through weeks of him not being able to pay at all. It would take him 3 or 4 weeks sometimes to catch up what he owed my bf, we almost got evicted because of it and he literally would say "my bills come first ....." So obviously my bf quit. I had a HUGE suspicion that he wasn't actually paying in taxes and when it came time for taxes this year, wouldn't you know, my bf DID NOT receive a W2 or any type of anything. This man took thousands from him and kept it in his pocket. Who did we report this to? I want this man to suffer.

(Note that we have all of this documented. We have a copy of the W2 and pictures of the pay stubs that show the taxes supposedly withheld etc etc)

Side note: another thing is that he kept very expensive equipment/tools of my boyfriends. He signed an itemized list of the equip/tools that stated he did indeed have them in his possession and he would return them as soon as he returned home from out of time. Not only did he sign it, but he then texted a picture of it from his cell (said as the company phone). He never returner them. He blocked our numbers and we have never heard from him again. Would this be something I'd need to file separately, if so, where and with who?