Most SIXT rentals can easily be extended by up to 28 days – directly in the SIXT app or via "Manage booking" on the website. Billing follows a 24-hour cycle, so you'll always know exactly when an additional rental day is charged.
How to extend
Open the SIXT app or sign in on the website under "Manage booking"
Select your current rental
Adjust the return date and confirm the change
The extension takes effect immediately, provided the authorisation is successful
Longer than 28 days?
A direct extension is no longer possible in that case. Simply make a new booking – ideally online in advance, so the transition is seamless.
Extension not working? Two common reasons:
Payment method: Check whether you have sufficient balance or credit limit available
Vehicle has reached its maximum rental period: The vehicle is being taken out of the fleet. Make a new booking and swap to another vehicle at a SIXT branch
When is an additional day charged? All rentals are calculated on a 24-hour billing cycle:
Example 1: You pick up the vehicle on day one at 12:00 and return it on day two at 12:00 ? 1 day is charged
Example 2: You return the vehicle on day two at 13:00 ? an additional day is charged
This keeps your billing transparent and easy to follow.
Next step
Extend your rental now on the website or in the SIXT app.
Still need help? Find our contact options below – please have your rental agreement number ready.
If your extension doesn't go through in the app or under "Manage booking", it's usually down to one of these reasons: your payment method, the vehicle's maximum rental period or reaching the 28-day limit. Just message us on WhatsApp or Live Chat – we'll review your booking and find a solution together.
Common reasons
Payment method: Insufficient balance or credit limit for re-authorisation
Maximum rental period reached: The vehicle is being taken out of the fleet and needs to be swapped for another one
Extension beyond 28 days: A direct extension is no longer possible – a new booking is required
Quick fixes
Check your payment method and available credit limit
Try a shorter extension period
Make a new booking and swap to another vehicle at a SIXT branch if the maximum rental period has been reached
Still need help? Find our contact options below – please have your rental agreement number ready.
An extension is calculated at the daily rate of your booked tariff – so based on the rate agreed when you originally booked. If booked, your extras (additional driver, protection package, sat-nav, child seat) are added at their respective daily rates. You'll see the exact amount before you confirm.
How it's billed
The extension appears on your final invoice at return.
Next step
Check your extension price on the website or in the SIXT app.
Still need help? Find our contact options below – please have your rental agreement number ready.