Yes, terms can still move after signing, but your leverage peaks before you sign, so do as much of the negotiating as possible up front. Requests like a credit toward closing costs or a rate buydown normally belong in your initial offer. That's when you have the most power to win them. Once you're under contract, some things can still be negotiated. Repair-type credits are an example, though those barely apply to brand-new construction anyway. Whatever you want to renegotiate needs to happen before your contingencies are removed. After you release contingencies, you've signaled you're committed, and there's very little leverage left to push with. Any change to the agreed terms gets papered as an addendum to the purchase contract, so both sides are bound to the new terms instead of relying on a verbal understanding. The practical order: negotiate hard before you sign, protect your remaining leverage until contingencies come off, and get anything you agree to in writing. If you're buying new construction, a free Roadmap conversation early on can help you figure out which incentives are worth pushing for before you're locked in.