Legal Question in Real Estate Law in California

Re: Does person paying half of rent, have to be on rental agreement

Renting someone's property is a matter of private agreement. The prospective tenant can require the landlord to do whatever the prospective tenant can get away with asking for, such as demanding that the rooms be painted chartreuse and fuchsia. The landlord will probably say no, but who knows? Or, the landlord can require that the rent be paid every Tuesday, in nickels and dimes. The tenant will probably say no, but who knows? If landlord and tenant can't agree, tenant will rent somewhere else, and landlord will look for other tenants.

It's the same with whether everyone has to sign the rental agreement. The landlord has the right to demand it, and the tenant can then say yes or no. If the answer is no, at the end of the notice period (or the term of the lease, if there is one), the tenant will be moving on. It works both ways, of course; the tenants could say, for example, either give us new carpets or we'll move.

What I'm trying to say is that it's a free country, more or less, and landlords and tenants are free to negotiate. Either party can make unreasonable demands as well as reasonable requests upon the other.

There are a few limitations on the freedom of landlords and tenants to bargain for their own terms. Landlords can't discriminate based on race, religion, age (in most cases), sexual preference, etc.; they can't demand excessive deposits, can't demand waivers of liability for their own negligence, and a few other things. Neither tenants or landlords can "break" leases without liability. Other than that, the deal between a landlord and a temant is pretty much whatever the two parties can negotiate.