Legal Question in Real Estate Law in California

That would entirely be a matter of local zoning and business ordinances. There are IRS and FTB regulations on deductibility of home offices and related expenses that you have to comply with to take the deductions, but nothing you have to comply with in order to do it. As long as you use it for your residence as well, it will never be anywhere near 100% deductible, but beyond that a good tax accountant can tell you as much or more than a lawyer. As for any other legalities, it will be entirely a matter of what your local government allows and requires in regard to home-based businesses in residential areas. So you will have to check with city hall, or your county offices if you are not within the city limits of an established city jurisdiction.

If the proposed office-at-home is in Sherman Oaks, I'd start with the Sherman Oaks Chamber of Commerce, which probably has a staff person who can look up the zoning at the address proposed for your office-at-home. Since it's a part of the City of Los Angeles, that's whose rules you'd have to follow. I'd suspect that your proposed use would be permissible with a special-use permit, requiring an application and perhaps a public hearing, but depending upon the exact location it could also be permissible without a variance -- or totally impermissible.