
How do you apply for business tax registration certificate in Los Angeles
You just have to fill out the Business Tax Application form you can avail from the Office of Finance at North Spring Street Los Angeles. You will also be given two options on how to submit your form after you have able to fill it out. Your can either send it personally to their office or send it via email.
http://finance.lacity.org/pdf/TaxRegistrationV4.pdf
In the form you will be ask to provide 6-digit primary and secondary business activity code which will be reported on your federal tax return. This lists the all the codes available
http://finance.lacity.org/pdf/NAICSCODES.pdf

