Pentest Letter of Attestation Sample: 8 Templates for MSPs [2026]

A letter of attestation is official proof that a penetration test was done. It's a document your client can show to customers, auditors, and business partners saying "we had security professionals test our systems and confirm they're secure."

For MSPs, vCISOs, and penetration testing companies, letters of attestation are a critical part of the deliverable. Many clients won't do a pentest unless you provide one.

This guide shows you eight letters of attestation templates you can customize and use immediately.

Why Letters of Attestation Matter

Penetration testing is not just about finding bugs. It's about demonstrating to the world that your client takes security seriously.

A letter of attestation is proof. It says:

• To customers: "We test our security regularly"
• To auditors: "We comply with security best practices"
• To business partners: "You can trust us with your data"

Without a letter of attestation, the pentest is just a report sitting in a drawer.