Legal Question in Business Law in California

That the company is acting as if the contract was signed is strong evidence that it intends to abide by the contract's terms, but it is not as good as a signed contract. Contracts usually have many terms in addition to the amount and schedule of payments, and those terms are often revised or replaced during negotiations. The company could argue that the document you call the actual agreement was really just a draft. (That may sound far-fetched, but I've seen it happen.) If such a dispute went to court, the jury would have to decide whom to believe.

I don't think the fact that you have been working, and being paid, for six months lends much support to the validity (enforceability) of an unsigned contract. Many workers don't have written employment contracts at all. I have done a fair amount of research (in the past) on the enforceability of unsigned contracts, leading me to conclude that in some cases the contract can be treated as an offer by the writer, and the performance by the recipient constitutes acceptance and completes the contract. Thus, if I write a letter to Joe offering to pay him $5,000 if he paints my house, and he paints my house, we are in contract and the terms can be ascertained from my letter, even though Joe didn't sign it (and maybe I didn't sign it, either). (Contracts of this sort are sometimes called 'unilateral' contracts). However, in the employment context, it is so commonplace for an employer-employee relationship to arise without any writing, a court (or jury) is likely to consider an unsigned contract document as an offer that was refused, or as Mr. Hoffman says, a draft.