You can correct a UK ETA application mistake before payment is completed, but after payment, the application generally cannot be changed.
If you entered important details incorrectly, such as your passport number, name, date of birth, or nationality, you may need to apply again with the correct information.
A UK ETA is linked to the passport details used in the application, so an incorrect passport number can cause problems when traveling.
Before paying and submitting your UK ETA application, carefully check your passport details and personal information.