Certificate vs. Affidavit of Mailing: What’s the Difference?

When it comes to compliance and legal documentation, just sending mail isn't always enough. Whether you are delivering tax notices, employment termination letters, or lease violations, you often need proof that the letter was mailed. That’s where Certificates of Mailing and Affidavits of Mailing come in.

Though they may sound similar, these two documents serve different purposes. In this article, we’ll explore their differences, use cases, and legal value, and how Certified Mail Labels makes it easy to get both, at no additional cost, with every Certified and First-Class Mail piece.

What Is a Certificate of Mailing?

USPS-Validated Proof of Acceptance

A Certificate of Mailing is a receipt issued by the United States Postal Service (USPS) that confirms a mail item was accepted into the mail stream on a specific date. It provides official proof of mailing—ideal for meeting legal deadlines or regulatory compliance.

This certificate does not include delivery tracking or confirmation. It strictly validates that the item was mailed from a specific location, on a specific date.

Common Uses

Certificates of Mailing are commonly required in:

• Tax filings and IRS deadlines
• Court-ordered notices
• Homeowners association (HOA) notices
• Government communications
• Employment-related documentation

These certificates are widely accepted in legal and government settings when timely mailing must be proven.

What Is an Affidavit of Mailing?

A Signed Statement from the Sender

An Affidavit of Mailing is a signed declaration verifying that the sender prepared and mailed a document to the intended recipient. It typically includes the name and address of the recipient, mailing date, and description of the contents.

Unlike a Certificate of Mailing (which comes from USPS), an Affidavit is generated by the sender or mailing service provider. In some jurisdictions, an affidavit may be notarized for additional legal credibility.

When Is an Affidavit of Mailing Used?

This document is often used to supplement a Certificate of Mailing, particularly in:

• Court filings
• Lease termination letters
• Compliance and regulatory correspondence
• HR notices
• Landlord-tenant communications

Affidavits help establish that a responsible party mailed the document as described and can be invaluable in disputes or audits.

Certificate vs. Affidavit of Mailing: Key Differences

Why You May Need Both

Legal Protection and Compliance

Using both a Certificate of Mailing and an Affidavit of Mailing provides layered protection in the event of a legal or regulatory dispute. The certificate shows the item was mailed; the affidavit adds a declaration of what was mailed and by whom.

This combination is particularly useful in:

• Wage dispute cases
• Lease termination timelines
• Benefit eligibility deadlines
• Tax penalty appeals

Proactive Documentation

In today’s compliance-focused business environment, being able to prove not just that a piece of mail was sent, but when, how, and by whom can protect against penalties, lawsuits, and lost time.

Certified Mail Labels Provides Both—At No Extra Cost

At Certified Mail Labels, both a Certificate of Mailing and an Affidavit of Mailing (when selected) are available for every Certified Mail and First-Class Mail letter created on the platform at no additional cost.

Here’s how Certified Mail Labels stands out:

Skip the Trip to the Post Office

No need to wait in line or fill out physical forms. Users can log into their Certified Mail Labels account, create a label, and mail their document right from home or the office.

Automatically Generated Documentation

With each mailing, Certified Mail Labels generates:

• A USPS postmarked Certificate of Mailing
• A timestamped Affidavit of Mailing (when selected)
• Real-time USPS tracking
• A secure record in your account’s 10-year compliance archive

All documents are available 24/7/365, which is invaluable for audits or legal reviews.

Affordable and Flexible

• No monthly fees
• No long-term contracts
• No special equipment needed
• Pay as you mail

Whether you’re mailing a single document or thousands, Certified Mail Labels fits your workflow and budget.

Bulk & Automated Mailing Options

For organizations with recurring mailing needs (like lease renewals, rent increases, or employee notices), Certified Mail Labels also offers:

• Excel batch processing
• API and SFTP integrations for automated mailing from system to system
• Same-business-day print, pack, and mail fulfillment available for uploaded PDFs

Who Benefits Most?

Certified Mail Labels is the trusted choice for:

• Property managers
• Law firms
• Government agencies
• HR departments
• Tax professionals
• Financial institutions
• Healthcare organizations

Whether you're sending 1 piece or 1,000, the platform offers the documentation and support to help you stay compliant, save time, and avoid costly mistakes.

Get the Proof You Need—Every Time You Mail

When legal or regulatory compliance is at stake, verifying your mailing isn’t optional—it’s essential. Both the Certificate of Mailing and the Affidavit of Mailing serve as vital forms of documentation, often required by courts, agencies, and auditors.

With Certified Mail Labels, both forms are available, at no extra charge, with every Certified or First-Class Mail label. Backed by a secure 10-year archive, an easy online platform, and the ability to automate recurring mailings, Certified Mail Labels is the smart solution for anyone who needs reliable proof of mailing.

Schedule a Live Demo to see our platform in action.