Sole proprietor , used SSN, now i have and EIN, which to file with?

I own a business as a sole proprietor. I used my social security number to file for the past 10 years. This year I got an EIN because I was having to give a 10-99 to s contractor, and i did not want them to have my social security number. I want to know when I go to file my taxes, do I use my Social security number or my EIN>?