How to Add TSA PreCheck to Your Southwest Flight After Checking In

You cannot add TSA PreCheck to a specific flight after you have already checked in

TSA PreCheck is a program you enroll in separately from any airline booking. Once you are enrolled, TSA PreCheck appears on all your boarding passes automatically — but only if your airline has your Known Traveler Number (KTN) linked to your reservation before you check in. After you check in, the boarding pass is already printed or digital, and it cannot be changed to add PreCheck status.

If you checked in without PreCheck on your boarding pass, you have two options: you can still go through the PreCheck lane at security if you show your PreCheck card or membership number to the TSA officer, or you can contact Southwest before your flight to add your KTN to the reservation and request a new boarding pass.

Key Takeaways

TSA PreCheck must be linked to your Southwest reservation before you check in for the boarding pass to show PreCheck status.
If you already checked in without PreCheck, you can still use the PreCheck lane at security by showing your physical PreCheck card or membership number to the TSA officer.
To add your KTN to an existing Southwest reservation, call Southwest reservations at 1-800-I-FLY-SWA or use the Manage Reservations tool on Southwest.com if you have not yet checked in.
Adding your KTN after checking in may result in a new boarding pass, but it will not change your current one — you will need to request a replacement at the airport.

How to add your KTN before you check in

If you have not yet checked in, you can add your TSA PreCheck number to your Southwest reservation through the Manage Reservations tool on Southwest.com. Log in with your confirmation number and name, find your reservation, and look for the option to add or update your Known Traveler Number. Enter your nine-digit KTN exactly as it appears on your TSA PreCheck card, then save the changes.

You can also call Southwest reservations at 1-800-I-FLY-SWA (1-800-435-9792) and ask a representative to add your KTN to the reservation over the phone. Have your confirmation number and PreCheck membership number ready. Once the KTN is added, check in online, at a kiosk, or at the counter, and your boarding pass should display PreCheck status.

What to do if you already checked in without PreCheck

If your boarding pass does not show PreCheck but you are enrolled in the program, you can still access the PreCheck security lane. Bring your TSA PreCheck card or your membership number and show it to the TSA officer at the checkpoint. The officer can verify your PreCheck status and direct you to the PreCheck lane even if your boarding pass does not display it.

If you want your boarding pass to show PreCheck for future reference or for airline benefits, call Southwest at the airport or before your flight and ask them to add your KTN to the reservation and issue a new boarding pass. This does not change your seat or boarding position — it only updates the document. Some airports allow you to print a new boarding pass at a kiosk if you update your reservation through the Manage Reservations tool on your phone.

Why PreCheck status did not appear on your boarding pass

The most common reason PreCheck does not show on a Southwest boarding pass is that your KTN was never added to the reservation. Southwest does not automatically pull your PreCheck information from TSA — you have to manually enter your nine-digit KTN into your booking.

Another reason is that you entered your KTN incorrectly. PreCheck numbers are nine digits and must match exactly what TSA has on file. If you are unsure of your number, log into your TSA PreCheck account at tsa.gov or check your PreCheck card. A third reason is that you checked in before the KTN was added to the reservation — the boarding pass is generated at the moment you check in, so any changes made after that point will not appear on the same pass.

Adding your KTN to future Southwest bookings

To avoid this problem on your next flight, add your KTN when you first book your ticket. During the booking process on Southwest.com, there is a field for Known Traveler Number. Enter your nine-digit PreCheck number there, and it will be part of the reservation from the start.

If you book through a travel agent or a third-party site, ask them to include your KTN in the reservation details. You can also add it later through Manage Reservations on Southwest.com or by calling reservations, but adding it at booking time is the simplest approach and ensures PreCheck appears on your boarding pass when you check in.

What your PreCheck card or membership number shows

Your TSA PreCheck membership number is a nine-digit code printed on your PreCheck card. It is also called your Known Traveler Number or KTN. This is the number you enter into airline reservations. Your PreCheck card itself is your proof of enrollment and is what you show to TSA officers if your boarding pass does not display PreCheck status.

Your PreCheck membership is valid for five years from the date you were approved. You can check your membership status and expiration date by logging into your TSA PreCheck account at tsa.gov. If your membership is expired, you will need to renew it before PreCheck benefits explore to new bookings.

Frequently Asked Questions

Can I use the PreCheck lane at security if my boarding pass does not show PreCheck?

Yes. Show your TSA PreCheck card or membership number to the TSA officer, and they can verify your status and direct you to the PreCheck lane. Your boarding pass does not have to display PreCheck for you to use the benefit at the checkpoint.

Will adding my KTN after I check in change my seat or boarding group?

No. Adding your KTN to the reservation after you check in does not affect your seat assignment or boarding position. It only updates the boarding pass document itself. You will need to request a new boarding pass at the airport or through the airline if you want the updated version.

What if I do not know my TSA PreCheck number?

Log into your TSA PreCheck account at tsa.gov with your username and password, and your nine-digit membership number will be displayed. You can also find it printed on your physical PreCheck card. If you cannot locate it, contact TSA at 1-855-347-8371.

Can Southwest add my PreCheck number to my reservation if I am already at the airport?

Yes. Go to a Southwest ticket counter or call Southwest at the airport, and a representative can add your KTN to the reservation and print a new boarding pass. This usually takes a few minutes and does not require you to check in again.

Do I need to add my KTN every time I book a Southwest flight?

Yes. Each reservation is separate, so you need to add your KTN to each booking. You can do this when you first book, through Manage Reservations before you check in, or by calling Southwest reservations.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.