A: Hello! Just to be clear, I am not licensed to practice in Texas, but I am a licensed attorney in Oklahoma. I have seen this question be unanswered for a while, so I thought I'd respond. Typically, once the parties have both agreed (by writing and signing) terms of a contract, including a maturity date for payment, the maturity date can only be changed by all parties in another signed writing. That means that one party (such as the owner finance seller) should not be able to change the payment terms of an agreement without your express approval. Hope that helps!