What a Known Traveler Number Does and Where to Enter It

Your Known Traveler Number (KTN) is a unique identifier that tells the TSA you have passed their background check for PreCheck. When you enter your KTN during flight booking, the TSA can match your reservation to your PreCheck status before you arrive at the airport. This means you go through expedited screening instead of standard security lines.

The KTN itself is just a string of numbers and letters — usually 10 to 15 characters long. You receive it by email after TSA approves your PreCheck process, typically within three to five business days of your in-person appointment. Keep this number handy; you will need it every time you book a flight.

Without your KTN in the reservation, the TSA cannot see that you have PreCheck, even if your process was approved. The airline's system and the TSA's system do not automatically talk to each other. You have to make the connection yourself by entering the number during booking.

Key Takeaways

  • Your KTN must be entered into your airline reservation at the time of booking, not added later, for the TSA to recognize your PreCheck status.
  • The KTN appears in your TSA PreCheck approval email and is also stored in your TSA account online.
  • Each airline has a different field or form section for KTN entry, usually labeled "Known Traveler Number," "Trusted Traveler," or "PreCheck," depending on the carrier.
  • If you forget to add your KTN during booking, you can often add it through the airline's website or app before check-in, though some carriers have cutoff times.
  • Your KTN does not expire as long as your PreCheck membership is active, but you must renew your PreCheck every five years to keep the number valid.

Finding Your KTN in Your Email and TSA Account

When the TSA approves your PreCheck process, they send a confirmation email to the address you provided during enrollment. This email contains your KTN in the body of the message, usually near the top. Search your inbox for "TSA PreCheck" or "Known Traveler Number" if you cannot find it when ready. Check your spam folder as well — some email providers flag TSA messages incorrectly.

You can also log into your TSA PreCheck account at the official TSA website. After signing in with your credentials, your KTN appears on your account dashboard or in a section labeled "Your PreCheck Details" or "Membership Information." This is the most reliable place to look if you have lost the original email or cannot locate it quickly.

Write down your KTN and store it somewhere you can access it easily — your phone notes, a password manager, or a travel folder. You will use it multiple times per year if you fly regularly, so keeping it visible saves time at booking.

Entering Your KTN During Airline Booking

The process of adding your KTN varies slightly by airline, but the principle is the same: you enter it into a field during the booking process, usually on the passenger information page. Most airlines ask for it after you enter your name, date of birth, and frequent flyer number.

On airline websites, look for a field labeled "Known Traveler Number," "Trusted Traveler Number," "PreCheck," or sometimes "TSA PreCheck ID." Some airlines group it under "Additional Information" or "Security Information." If you are booking through a third-party site like Kayak or Google Flights, the option may not appear at all — in that case, you will need to add it directly through the airline's website or app after you complete the booking.

When booking by phone with an airline agent, straightforward tell them your KTN and they will enter it into the reservation. Spell it out letter by letter to avoid errors, since a single wrong character means the TSA will not recognize your PreCheck status.

Adding Your KTN After You Have Already Booked

If you forgot to enter your KTN during booking, you can usually add it later through the airline's website or mobile app. Log into your reservation using your confirmation number and last name, then look for an option to "Edit Passenger Information" or "Manage Booking." The KTN field should appear there.

Most airlines allow you to add or change your KTN up until 24 hours before departure, though some have earlier cutoff times. Check the specific airline's policy if you are cutting it close. If you are within a few hours of your flight and cannot add it online, call the airline directly — agents can often update it manually even after the online window has closed, though there is no may provide.

If you add your KTN after booking, the TSA system may not have time to update before your flight. To be safe, arrive at the airport a bit earlier than usual and bring your PreCheck approval email or a screenshot of your TSA account showing your KTN. This gives the TSA agent at security a way to verify your status manually if the system has not caught up yet.

What Happens at Security When Your KTN Is in Your Reservation

When you check in for your flight, the airline sends your reservation details to the TSA, including your KTN. The TSA matches that number to their database and flags your boarding pass with a TSA PreCheck indicator — usually a checkmark, the word "TSA Pre✓," or a specific code depending on the airline.

At the security checkpoint, the TSA agent scans your boarding pass and sees that indicator. You then proceed to the PreCheck screening lane, where you keep your shoes, belt, and light jacket on, leave your laptop and liquids in your bag, and move through the process faster than standard screening. The whole experience typically takes five to ten minutes instead of 20 to 30.

If your boarding pass does not show the PreCheck indicator, tell the agent at the checkpoint that you have PreCheck and provide your KTN. They can look it up manually, though this takes longer. This is why entering your KTN during booking is important — it prevents delays and confusion on the day of travel.

Troubleshooting When Your KTN Is Not Working

If you entered your KTN correctly but your boarding pass does not show the PreCheck indicator, the most common cause is a mismatch between the name on your reservation and the name on your TSA PreCheck approval. The TSA system is very strict about exact matches. If your reservation says "Robert" but your PreCheck approval says "Robert James," the system will not connect them.

Check that your first name, middle name (if you provided one), and last name match exactly between your airline reservation and your TSA account. Spaces, hyphens, and punctuation must be identical. If there is a mismatch, contact the airline and ask them to correct your reservation to match your government-issued ID and TSA account.

Another possibility is that your PreCheck membership has expired. PreCheck is valid for five years from your approval date. If your five years are up, your KTN is no longer active, and you will need to renew your PreCheck membership before the number works again. Check your TSA account to see your membership expiration date.

If your name matches, your membership is active, and you entered the KTN correctly, contact the airline's customer service with your confirmation number and KTN. They can investigate whether the reservation was processed correctly. In rare cases, a technical glitch prevents the KTN from syncing with the TSA system, and the airline may need to resubmit your information.

Keeping Your KTN Safe and Updated

Your KTN is not classified as sensitive information like a Social Security number, but you should still treat it as personal data. Do not post it on social media or share it in unsecured messages. Store it in a password manager or a private note on your phone so you have it when you need it but it is not visible to others.

If you lose your KTN or forget it, you can always retrieve it from your TSA account online or request it by contacting the TSA directly. You do not need to pay anything or go through a new process process — the number is permanently tied to your PreCheck membership as long as it is active.

When you renew your PreCheck after five years, the TSA will issue you a new KTN. Update your records and start using the new number for all future bookings. The old number will no longer work once your membership expires.

Frequently Asked Questions

What if I do not have my KTN when I book my flight?

You can leave the KTN field blank at booking and add it later through the airline's website or app, as long as you do so before the airline's cutoff time (usually 24 hours before departure). If you wait too long, call the airline directly and provide your KTN over the phone so an agent can add it manually.

Can I use the same KTN for flights on different airlines?

Yes. Your KTN is issued by the TSA and works with every airline. You enter the same number every time you book a flight, regardless of which carrier you are flying.

Do I need my KTN if I am traveling internationally?

TSA PreCheck only applies to domestic flights within the United States. For international travel, you may be interested in Global Entry, which includes PreCheck benefits and also speeds up customs screening when you return to the U.S. Global Entry has its own trusted traveler number, which is different from your PreCheck KTN.

What if my boarding pass does not show PreCheck even though I entered my KTN?

First, check that your name on the reservation matches your TSA account exactly — even small differences like "Bob" versus "Robert" will cause the system to not recognize your PreCheck. If the names match, verify that your PreCheck membership has not expired. If both are correct, contact the airline with your confirmation number and KTN so they can investigate the booking.

Can I add my KTN to a ticket someone else bought for me?

Yes, as long as the reservation is in your name. You can add your KTN through the airline's website using your confirmation number and last name, or you can ask the person who booked it to add it for you. The KTN must match the passenger name on the ticket.