I have been doing lawn maintenance for the past 8 yrs or so. I do this part time, but lately I have been getting more and more commercial biz. I used to just file my taxes at the end of the year. But now my c.p.a has sent me tax i.d. number, I haven't done anything with it though. I am now starting to do alot of installation and buying from wholesail. How will my tax i.d. number help me???