I work for a nonprofit and we're improving our vendor onboarding process. We regularly collect W-9s, ACH payment details, tax IDs, and occasionally Social Security numbers from sole proprietors. What secure methods are other organizations using to collect this information? Once received, is Microsoft 365—particularly a dedicated SharePoint site—appropriate for storing these documents with strong access controls, or is a dedicated vendor-management or document-management system a better choice? We're trying to balance security, compliance, vendor convenience, and cost.
4 Answers
If you don’t need a document online indefinitely, a dedicated encrypted intake portal with automatic deletion after transfer may be simpler than trying to secure every part of Microsoft 365. Don’t forward sensitive documents by email, even internally. If paper copies are required, keep them in a restricted, locked filing area and remove the electronic copy from the intake system once the approved record has been created.
SharePoint can be a reasonable storage location if it’s set up as a separate site with its own tightly controlled membership group, rather than as a folder or channel inside a broad team. Use MFA, compliant-device policies, audit logging, retention and deletion rules, and a default sensitivity label with encryption so protection remains attached if a document is downloaded. The bigger risk is often collection: avoid email attachments and unprotected forms. Use a secure vendor upload workflow that limits access and keeps the file out of ordinary mailboxes. Also document a callback procedure for ACH changes—call a known number already on file, not a number supplied in a change request.
Collection is usually where the biggest leaks happen. An emailed W-9 can remain in the vendor’s sent folder, your mailbox, backups, archives, and multiple other systems before anyone applies a SharePoint control. A secure, link-based upload portal that sends the document directly into a controlled repository is safer. Establish a rule that documents received by email are moved into the approved system and the original message is deleted according to your retention policy. Also confirm whether an EIN can be used instead of an SSN for a sole proprietor—reducing the amount of sensitive data collected is the simplest security improvement.
The platform matters, but the operating controls matter just as much: restrict access to the minimum necessary group, require strong authentication, maintain audit logs, define retention and destruction schedules, review permissions periodically, and test the ACH-change verification process. Whether you choose SharePoint or a specialized system, make sure vendors have a secure upload path and that staff know exactly how to handle exceptions.
That matches how we’ve configured our SharePoint site so far: limited membership, MFA, sensitivity labels, and Conditional Access for compliant devices. I’m still trying to determine the best way to let external vendors upload files directly, since the built-in file-request feature may be limited to OneDrive rather than SharePoint libraries. We may need a dedicated secure intake portal or vendor-management tool instead.