Legal Question in Business Law in California

Re: company promissory note

Four years is indeed the statute of limitations for actions based on a written contract, and it's measured from the date of breach.

However, lawyers are reluctant to go further and say the debtor is out of the woods or that the creditor is out of luck. Various circumstances can "toll" (pause the running) of the statute; or there may be an alternate theory of recovery that has a different starting point for the clock, such as "account stated" or "book account."

An account stated, for example, can be treated like a brand-new written contract, and can arise when the creditor sends a bill and the debtor makes a new promise to pay, or a partial payment, even though no suit was filed then.