Legal Question in Construction Law in California

Re: deliquent billing

If he sues within 4 years, you'll get the answer to that from a judge or jury. Until then, try to negotiate or settle in a way fair to you.

Re: deliquent billing

Neither being six months delinquent in delivery to you nor your being six months delinquent in paying a bill or item of a bill would affect your legal duty to pay, as far as I know. I did a quick search for laws that might require a drilling contractor to submit a final bill within some time period, but did not find any. I hasten to add that this doesn't mean no such law exists - only that I don't know of it.

I think the more important issue here is whether you would have been required to pay this additional amount ever, even if billed for it instantly. Figuring this out would require careful review of the written contract. Anything you were told but differs from the written contract is probably not enforceable. However, if this is a time-and-materials contract rather than for a fixed bid price, you or the contractor may have to prove your positions based on his field records and your observations and measurements of what was done.

If the amount in dispute is under $7,500, consider paying under protest and going to small claims court to recover the sum paid.