Had an email from TfL earlier today, the minimum auto top-up amount on Oyster PAYG is being reduced to £10 from 30th March.
From Wednesday 30 March, there will be an additional Auto top-up option of £10. From this date you will be able to change your selected Auto top-up amount to £10 via the ‘Manage Auto top-up’ page in your account.
The existing Auto top-up options of £20 or £40 will continue to be available and your chosen top-up amount will remain the same. You will not need to take any action if you wish to keep your Auto top-up amount the same.
We're amending the terms and conditions to reflect this change, but you won't need to sign up again.