Before giving a contractor — a freelance developer, an outsourced ops person, an agency — access to systems that touch customer data, an NDA is necessary but not sufficient on its own. An NDA is a legal promise not to disclose information; it doesn't say anything about how that access is granted, scoped, or removed, which is what a SOC 2 or ISO 27001 auditor is actually going to ask about.
What to have in place beyond the NDA
Least-privilege access, granted explicitly. The contractor should get access to the specific systems and data they need for their work — not a blanket account with everyone else's permissions. Document what was granted and why, the same way you would for an employee (see Performing Access Reviews if you're tracking this in ComplyJet).
A defined end date or offboarding trigger. Contractor engagements end; access should end with them. Treat contractor offboarding with the same rigor as employee offboarding — same deprovisioning checklist, same audit trail — rather than letting an account linger because "they might come back."
A data processing or security addendum, if the engagement is substantial. For anything beyond light-touch access, many companies use a more specific agreement than a generic NDA — covering things like where data can be stored, whether it can leave your environment, and what happens to it at the end of the engagement. Your legal counsel is the right source for the actual template; this isn't something to improvise from a search result.
The same background-check and training expectations you'd apply to an employee, scaled to the level of access — a contractor with production database access is a bigger control gap than a designer with none, and your evidence should reflect that difference rather than treating "contractor" as automatically lower-risk.
What auditors are actually checking for
The underlying question an auditor is asking isn't "did you have them sign something" — it's "can you demonstrate that access was intentional, scoped, and time-bound." An NDA on file answers a confidentiality question; it doesn't answer that one. Treating contractors as a distinct, tracked category in your access reviews (rather than folding them silently into your general employee list) is usually the cleanest way to keep this demonstrable.