This is one of the most common pressure tactics we see, and the short answer is: not without real consequences on their side either. From a legal insight standpoint, your right to payment for work already performed generally exists independent of any new contract the client wants you to sign — they cannot typically condition payment for completed services on your acceptance of new terms, as that may constitute breach of your original agreement. Before you sign anything, have someone review what the new vendor agreement actually changes — scope limitations, IP ownership, liability waivers, and non-solicitation clauses buried in boilerplate can cost you far more than the invoice is worth. Bring the original contract and the new agreement to a consultation so we can walk through the leverage points and help you respond from a position of clarity, not panic.