When is the final payment for whole-house customization due?

When the final payment is due depends mainly on what the contract says. There are two common arrangements in the industry: pay after installation is complete and acceptance inspection passes, or retain a small portion as a warranty deposit and settle it later. It is advisable to tie payment milestones to acceptance criteria—for example, pay after cabinet bodies are installed in place, door panel gaps and opening/closing work properly, and edge finishing is complete. Before paying, list all issues in a checklist and settle only after they are rectified; this is far less troublesome than chasing repairs afterward. The specific percentage and timing are subject to the contract you sign; do not rely on verbal promises alone.