Whether some parts of the contract is off limits matters not. When you are paying a service provider to do work for you then you have an absolute OBLIGATION to audit the books. That was what I did. Audit the books/records of subcontractors to whom our company paid Millions of dollars each year. We also ran physical inventory audits twice a year. It was stipulated in the contract. What kind of person would commit $300 million to a company and keep hands off?