When a bill, court notice, or tax form tells you to enclose a payment, it means putting your check or money order inside the same envelope as the return stub or form so the recipient can match your money to your account. The instruction is literal: the payment and the paperwork travel together in one mailing, not separately. Doing it correctly keeps your payment from being misapplied, delayed, or lost in a processing queue.
You will see this phrasing on utility bills, insurance invoices, government notices, court-ordered payments, and IRS forms. In every case, the sender is asking for the same thing: a payment instrument placed in the envelope alongside whatever identifying paperwork came with the bill.
What to Put in the Envelope
A complete payment package has three pieces: the payment instrument, the return stub or coupon that came with your bill, and the account information written on the instrument itself. If any of these is missing, your payment can end up credited to the wrong account or sitting in a processing exception queue.
The payment instruments you can enclose are personal checks, cashier’s checks, certified checks, and money orders.
- Personal check. Drawn directly on your bank account. This is the standard for routine bills and gives you a built-in paper trail once the check clears.
- Cashier’s check. Issued by the bank itself. The bank pulls the funds from your account upfront and guarantees payment, which is why recipients prefer it for larger amounts. Fees at major banks typically run $3 to $11.
- Certified check. A personal check your bank stamps and verifies. The check still draws on your account, but the bank confirms the funds are set aside.
- Money order. A prepaid instrument available at post offices, banks, and many retail stores. USPS domestic money orders cost $2.55 for amounts up to $500 and $3.60 for amounts between $500.01 and the $1,000 maximum. Retail stores often charge less. Money orders are a practical option if you do not have a bank account.1USPS. Domestic Extra Services and Fees – Notice 123
Do not enclose cash. Cash cannot be traced or recovered if the envelope is lost or stolen. If you need to pay in cash, look for an in-person option instead.
What to Write on the Check or Money Order
The information you write on the instrument itself is what rescues your payment when the return stub gets separated from it in processing. Treat the check as if it will arrive alone.
On the memo line, write your account number, case number, or reference number from the bill. Some billers want more. The IRS, for example, asks you to include the tax year, the related form number, and your Social Security number directly on the check.2Internal Revenue Service. Pay by Check or Money Order
Write the payee name as it appears on your bill. Minor variations are not automatically fatal under the Uniform Commercial Code, which allows a payee to be identified by name, account number, or other means,3Legal Information Institute. Uniform Commercial Code 3-110 – Identification of Person to Whom Instrument Is Payable but matching the printed name avoids trouble at the bank.
Check that the numerical amount in the box matches the amount you write in words on the legal line. If the two conflict, the written words control.4Legal Information Institute. Uniform Commercial Code 3-114 – Contradictory Terms of Instrument A check that reads “$150” in the box but “one hundred five dollars” on the line is legally worth $105.
The Return Stub
Most bills include a perforated slip at the bottom with your account number and often a scannable barcode. Tear it off and place it in the envelope with your check. Do not staple, tape, or paper-clip the two together. High-speed processing equipment jams on fasteners, and a jammed envelope is a delayed payment.
If the bill came with a window envelope, position the stub so the recipient’s address shows through the window.
Protecting Your Payment From Theft
Check fraud tied to mail theft has risen sharply. Suspicious activity reports related to check fraud nearly doubled between 2021 and 2023.5FBI Internet Crime Complaint Center. Mail Theft-Related Check Fraud Is on the Rise A few habits cut your exposure significantly.
- Write with gel ink. Gel ink bonds with paper fibers and resists the chemical solvents thieves use to “wash” a check, erasing the payee name and amount so they can rewrite it to themselves. Black gel ink is the hardest to alter.
- Use a security envelope. Security-tinted envelopes have an interior pattern that blocks anyone from reading the contents by holding the envelope up to the light. Return envelopes supplied with bills usually have this feature already.
- Mail from inside the post office. Avoid leaving outgoing payments in your home mailbox or in outdoor collection boxes overnight. Hand the envelope to a postal worker or drop it in the lobby slot.
- Never mail a blank check. If a thief gets a signed check with no payee written in, you generally cannot recover the money once they fill in a name and cash it.6Consumer Financial Protection Bureau. I Wrote a Check, but It Was Stolen and Cashed by the Thief. What Can I Do?
Before mailing, take a photo or photocopy of the front and back of the check. If something goes wrong later, that image is the easiest way to document what you sent.
Postage and Proof of Mailing
Standard first-class postage for a one-ounce letter is $0.78. First-class letters can weigh up to 3.5 ounces, and large envelopes can weigh up to 13 ounces, with additional postage required above one ounce.7USPS. First-Class Mail and Postage Seal the envelope firmly so nothing shifts in the sorting machines.
When you need proof the payment was sent and received, which is common for court-ordered payments, legal settlements, and tax deadlines, use USPS Certified Mail with a return receipt. Certified Mail costs $5.30 on top of regular postage, and a return receipt adds $4.40 for a paper card or $2.82 for an electronic version.1USPS. Domestic Extra Services and Fees – Notice 123 The return receipt gives you the recipient’s signature, delivery date, and delivery address.8USPS. Return Receipt – The Basics
When the Postmark Date Decides Whether You Are On Time
For federal tax payments and certain other legal deadlines, the date you mail counts as the date you paid. Under federal regulations, a payment mailed through USPS is treated as received on the postmark date stamped on the envelope, even if it arrives after the deadline.9eCFR. 26 CFR 301.7502-1 – Timely Mailing Treated as Timely Filing and Paying This is sometimes called the mailbox rule.
The rule only helps if the postmark clearly shows a date on or before the deadline. An illegible or late postmark is a late payment, no matter when you dropped the envelope in the box. You carry the risk of getting a timely postmark, so mailing on the last possible day is a gamble.9eCFR. 26 CFR 301.7502-1 – Timely Mailing Treated as Timely Filing and Paying Certified Mail removes the guesswork: the postal employee postmarks your sender’s receipt at the counter, and that postmark is treated as the official mailing date.
Enclosing a Tax Payment to the IRS
Tax returns are the most common situation where “enclose payment” appears. If you owe money when filing a federal return, the IRS asks you to include Form 1040-V (Payment Voucher) with your check or money order. Make the payment payable to “U.S. Treasury,” not “IRS,” and write your name, address, daytime phone number, Social Security number, the tax year, and the form number on the check itself.2Internal Revenue Service. Pay by Check or Money Order
The IRS accepts personal checks, cashier’s checks, and money orders by mail. It does not accept cash. Do not send credit card numbers through the mail; card payments go through the IRS website or by phone. Use the address printed on your form instructions or on the notice you received, and send it by regular USPS mail. Private delivery services can slow processing.2Internal Revenue Service. Pay by Check or Money Order
If Your Payment Is Lost or Stolen
Check your bank account first. Most checks are debited within two business days of deposit, though the recipient’s bank can hold funds longer for larger amounts.10Consumer Financial Protection Bureau. How Long Can a Bank or Credit Union Hold Funds I Deposited? If the check has not cleared and you suspect it is lost, call your bank right away to place a stop-payment order.
A stop-payment order tells your bank not to honor the check if anyone tries to cash it. A written stop-payment is effective for six months and can be renewed. An oral stop-payment expires after 14 days unless you confirm it in writing within that window.11Legal Information Institute. Uniform Commercial Code 4-403 – Customer’s Right to Stop Payment Banks typically charge $15 to $36 for the service. Once the stop is in place, issue a replacement payment.
If the check was already cashed with a forged endorsement, state law generally shifts the loss to the bank that accepted the forged endorsement rather than to you. That protection usually does not apply if you mailed a check with the payee line blank. Someone who fills in their own name on a signed, otherwise-blank check is much harder to pursue.6Consumer Financial Protection Bureau. I Wrote a Check, but It Was Stolen and Cashed by the Thief. What Can I Do?
Report the theft to your bank, file a police report, and file a complaint with the U.S. Postal Inspection Service if you believe the envelope was stolen from the mail. The photocopy or photo you took before mailing becomes your documentation for the fraud claim.