Schedule C line B Business Code is a 6 digit number for your activity. Here are the IRS instructions for Schedule C. Business codes start on page 17.
http://www.irs.gov/pub/irs-pdf/i1040sc.pdf
See the FAQ on Business Codes,
https://ttlc.intuit.com/questions/1899356
If you can't find a code that applies, you can enter 999999.
