How to Mail Sensitive Documents Safely

Sensitive documents can include tax records, medical records, legal papers, bank information, identification documents, or anything else containing information you would not want exposed. Mailing them is sometimes unavoidable. The important part is knowing what the recipient actually requires and creating the right record of what you sent.

Before You Mail Anything

Start by confirming the recipient's instructions. Check the mailing address on the organization's official website or paperwork, confirm the deadline, and find out whether they need an original or will accept a copy. Once you have the right destination, our ZIP+4 address lookup can help you check the postal format before writing the envelope.

We have another guide about mailing checks safely. I recently had to mail some rather large checks to pay off lenders and followed my own instructions. I ended up calling customer support for one of the lenders to verify the address because I found different answers online. Make sure you verify the address if anything looks unclear.

• Send copies instead of originals unless an original is specifically required.
• Remove or redact information the recipient does not need, if their instructions allow it.
• Make a complete copy or scan of everything you send.
• Use an attention line or department name when the organization provides one.
• Do not put Social Security numbers, account numbers, medical details, or other private information on the outside of the envelope.

Some tax forms, checks, payment coupons, and other documents require sensitive information inside the envelope. One of the lenders I paid required my account number on the payment coupon. Follow the recipient's instructions, but keep that information inside the sealed envelope.

How to Package Sensitive Documents

Use an envelope that cannot be seen through if possible. You do not want to advertise what you are mailing.

When we mailed checks recently, we wrapped them in another sheet of blank paper so none of the information could be seen through the envelope. We highly recommend doing that as an extra layer of privacy.

Seal the envelope completely and make sure no paper is caught in the flap.

USPS blue collection boxes are usually fine to use, especially if you deposit the envelope before the last collection time posted on the box. For large checks, original documents, or anything difficult to replace, we recommend handing the envelope directly to a postal employee or using the mail drop inside the Post Office.

Which Mailing Service Should You Use?

It kind of depends on what you are mailing. The three options covered here are Certified Mail, Registered Mail, and Priority Mail Express.

If timing matters, use our USPS delivery time estimator for a planning estimate, not a guaranteed arrival date. Allow extra time for delays and for the recipient to process your documents.

USPS Tracking

All three services give you tracking or delivery information, so you should be good there. If the documents are really important, do not just throw a stamp on the envelope. Use a trackable service and keep the mailing receipt.

Certified Mail

Certified Mail is especially useful when you need a mailing receipt and delivery tracking. You can send Certified Mail through our dashboard and keep track of everything in one place.

If you need the recipient's signature, add Return Receipt. You can choose an electronic Return Receipt or the physical green card that gets mailed back to you.

Registered Mail

Registered Mail is USPS's highest-security mail service. It is generally a better fit for valuable or irreplaceable items than ordinary paperwork. See our Registered Mail guide for more information.

Priority Mail Express

Priority Mail Express is the fastest option covered here and includes USPS Tracking. Use it when you need to get the documents there quickly. You can also request a signature record when purchasing it.

Common Sensitive Documents

What to Keep After Mailing

• A copy of every document and enclosure
• The date you mailed it
• The exact address used, including any department or attention line
• Your mailing receipt and tracking number
• The USPS delivery or attempted-delivery record
• The Return Receipt or signature record, if purchased