Quick clarification I give often: wages won’t reduce VA disability compensation, but they do count for VA pension and sustained substantially gainful employment can end TDIU. If you start working, report it promptly — pension income as soon as it changes, and for TDIU when you return to work — to avoid overpayments; VA may verify via SSA wage data or request VA Form 21-4140.
Example from last year: when I went back to 20 hrs/week on TDIU, I sent VA Form 21-4140 with my start date and first pay stub and asked for a written receipt, which kept me out of overpayment when the SSA wage match hit. If your hours spike or you think you’re near substantially gainful, “report it promptly” and keep a folder of stubs — it’s like flossing, annoying but saves pain; form link: About VA Form 21-4140 | Veterans Affairs.