In 2010, I did some work helping someone starting a new business. I did receive more than 600.00 for it. I am trying to file my taxes and was told I needed a 1099 and/or that the other person has to have a W-9 for me and should also send me a 1099. Will there be a penalty to either of us if I file without it? At the time, it wasn't something we thought about, but I don't want to have undeclared income. However, I don't want to pose them a problem wither since they did not have the paperwork on me. I know they don't plan to use any of it as a deduction on their own taxes, since the business did not really profit in 2010.