Contract Clause About Submission of Invoice

[beyondcomm]

My question involves independent contractors in the state of: California.

I work as an freelancer translator and interpreter. One agency had a clause stating "we must receive the invoice within 30 days otherwise we regret we will not be able to pay it". Is this clause legal? Can the client refuse to pay for a job that was performed to satisfaction, in which the freelancer incurred on expenses, if the invoice is not submitted within 30 days?
Client claims that late submission of invoices "wreaks havoc with cashflow" - however, the rate/price for services performed was clearly stated on contract.
I appreciate any thoughts.

[PattyPA]

What did your attorney say when you had your contract reviewed before you signed it? The time to question the enforceability of a contract clause is before you sign the contract, not after.

Having said that, there is a very easy way for this not to be a problem. Submit your invoices on time.