Morrisons customers who order their shopping online will now see a 5% holding “deposit” added to their bill.
The supermarket says this is to cover the cost of substitutions, so if an item you’ve ordered is out of stock and needs to be switched out with something else.
Morrisons will reserve the 5% deposit the day before your shop is delivered - so you won't be able to access these funds from this point.
You’ll then be emailed any substitutions that will be included in your shop, so you have a chance to review your order.
If no substitutions are needed, or if there is money leftover from any swaps, the deposit will then be issued back to you when your final bill clears within two days of delivery.
The amount you'll get back depends on how many items - if any - were swapped.
Shoppers have taken to Twitter to complain about the new deposit system.
What do you think of the new Morrisons 5% deposit on online orders? Let us know: mirror.money.saving@mirror.co.uk
One person said: "Safe to say I won't be using Morrisons delivery anymore!! We are in a cost of living crisis right now and they choose to introduce a extra 5% deposit on your shopping total in case of substitutions!
"I now have to wait till after the weekend for that 5% to clear and get it back..."
Morrisons used to reserve just £1 from to ensure your payment went through, before you’re fully charged after the order is complete.
A spokeswoman told MoneySavingExpert, which first reported the changes, that the 5% deposit would "ensure customers pay the correct amount for their online shopping".
"As a fresh food retailer, a lot of the food we sell does not have a fixed price as it depends on the size/weight of the product," she said.
"The money is held the night before the delivery is due and customers are only charged the final amount of their shopping."
Morrisons charges between £2.50 and £7 for delivery, depending on the time and day you want your order delivered, with a minimum spend of £40.
If you're a regular shopper, you might be able to save money by purchasing a delivery pass.
There is an anytime pass, which covers deliveries any day of the week, and this costs £8 for one month, £40 for six months, or £65 for one year.
Mid-week passes, which you can use for Tuesday, Wednesday and Thursday deliveries, are cheaper.
A monthly mid-week pass costs £5, or it is £20 for a six-month pass, or £35 for one year.
Morrisons isn't the only supermarket to make changes to its online delivery service in recent weeks.
Sainsbury's has upped the annual cost of its annual midweek delivery pass from £30 to £40 - an increase of £10, or around a third of the original price.
Customers have also complained on Twitter about its annual anytime delivery pass rising from £60 to £80.