Supermarkets across the UK have proposed introducing fuel deposits to fill up your tank at petrol stations. 

It means that you could have to pay £99 before even filling up your tank at Sainsbury's, Tesco or Asda. 

Here's what the changes mean for you, and how it will impact your spending...

How will the deposit system work? 

The system will require you to pay a deposit of £99 before filling your tank with fuel. 

Your bank or credit card issuer will then hold this deposit until the actual amount you paid for fuel is debited. 

This means that if you pay £40 for petrol, your bank will hold £99 until your £40 payment is processed. 

When the payment has been processed, your bank or credit card issuer will release the remaining £59 of your £99 deposit. 

This is known as "ringholding" which enables companies to protect their assets from incurring losses.

Why are supermarkets introducing the changes?

Tesco, Asda and Sainsbury's are all trialling the deposit scheme in order to reduce fuel theft and because card issuers such as Visa, Mastercard and American Express have changed the rules on payments.

The scheme aims to ensure that people have enough money in their account to fill up their tanks before leaving the petrol station, and to help customers keep track of their spending. 

What will happen if I don't have £99 in my account?

If you don't have £99 in your account, you should still be able to fill your tank up with fuel. 

If this is the case, the card issuer should show you a lower amount and tell you the maximum amount you can spend on fuel. 

However, it depends on your card issuer, as some may not allow you to pay less than £99. 

The advice in this case is to try another card, which could lead to problems in instances where you do not have another option. 

Will these changes definitely happen?

No, the £99 deposit scheme will not definitely be introduced. 

The new measures are currently being trialled at different locations across the UK. 

If the trials are successful then it's likely that the measures will be introduced on a permanent basis.