I recently got a job offer, and now I'm going through a background check with a contractor called HireRight. I seemed to pass on other parts of the background check, but they can't confirm for my employment at the startup I cofounded as the 2nd person.(startup of 4 people eventually) I was also the web developer and I have many emails from March including the one I confirmed to be a cofounder. Now Hireright is asking me for W2, 1099 forms or pay stubs to confirm my dates, but the problem is I didn't take any salary for the first 3 months.
So I started working full time in March, but we got funding in June. How can I make a good case that I indeed started working in March? I'm really frustrated that I went through a long process to land this job, and now a stupid background check is blocking me. So I really appreciate anyone that can give advice.