I have zero experience hiring software contractors, so forgive me if any of this sounds silly, my experience is in construction. Can you issue fixed price RFPs

I have zero experience hiring software contractors, so forgive me if any of this sounds silly, my experience is in construction. Can you issue fixed price RFPs instead of issuing T&M (I guess it would just be ‘T’ here) contracts? Whenever I hire construction subcontractors (which is frequently) I ask for a fixed price bid with a clear work scope and hold their feet to the fire if they forgot something that they should’ve included. For small jobs (under $25k) I will occasionally negotiate a T&M NTE (not to exceed) price while working with contractors I trust for jobs that have scope uncertainty (and a bucket of money to cover the worst case scenario) It’s entirely possible you have a contract where you get x number of bodies per hour for $y an hour. I would have a hard time trusting and managing a subcontractor without a fixed deliverable/scope of work with a definite end. Negotiating penalties/non-payment for non-working code/pull requests into your contract could help protect against fraud. It might be difficult/impossible to get a contractor to agree to terms like that. I don’t know if time tracking sheets would help as those can be doctored. In any case, I’d fire your current contractor and hire a new one, assuming you have the power to do so.