1. Professional Memberships: Information about relevant professional associations or memberships, useful when credibility needs to be established

2. Client References: List of major clients or projects, included when proof of active business operations is required

3. Financial Overview: Brief summary of business turnover or income, included when financial verification is specifically requested

4. Business Structure: Details about business structure (sole proprietorship, corporation, etc.), included when relevant to the letter's purpose

5. Insurance Coverage: Information about professional liability or business insurance, included when relevant to recipient's requirements

1. Business Registration Documents: Copies of business registration certificates or licenses

2. Tax Registration Proof: Copy of GST/HST registration or business number documentation

3. Recent Tax Returns: Copies of recent tax returns or notices of assessment (if required)

4. Professional Certificates: Copies of relevant professional certifications or licenses

5. Client Contracts: Samples of client contracts or service agreements (if appropriate)