Legal Question in Construction Law in California

Yes. Two percent of the unpaid amount per month plus attorneys fees to the prevailing party.

If this is a dispute between a property owner and prime contractor, then there is a 2% per month (24% per year) penalty for progress payments not paid within 30 days of when due (Civil Code 3260.1) and for retention not paid within 45 days of the date of completion (Civil Code 3260). This penalty is in lieu of statutory interest which is 10% per year. If the dispute is between a contractor and subcontractor, then the penalty is in addition to the statutory interest pursuant to Business & Professions Code section 7108.5 as to progress payments not paid within 10 days of receipt of funds from the owner.