Legal Question in Civil Litigation in California

Make a demand for payment. An oral demand is sufficient, but a written demand is better evidence.

Then, if no payment is made, bring an action in the appropriate court. If the money is owed to you, as an individual (as opposed to a corporation, LLC, or other types of entities), you can sue in small claims court for up to $7500. There are a few exceptions, but that is the general rule.

You may or may not have rights to recover attorneys fees in the action, and the amount of interest to which you are entitled depends on whether the note contains a provision for interest. Also, be sure to check the due date on the note. If there is a set due date, and it has passed, then you can move forward with the legal action. If there is no due date, then it is a "demand note," i.e. it is due, when you make demand for payment.

It might be a good idea to show the note to an attorney to see what rights you have, besides simply suing for the principal amount of the debt.

Also, watch the statute of limitations. For a written instrument, in California, you must bring your action within 4 years of the breach. For an oral agreement, in California, you must bring your action within 2 years of the breach.

Mr. Saltzman's answer is exactly correct. If you would like to consult with a local attorney, I am based in Walnut Creek, and have meeting facilities in San Francisco and Oakland. If you would like a no-obligation consultation, please let me know.