Does adding a fee at checkout sell more?

Yes: adding a fee at checkout sells more than showing it upfront. The CMA's evidence review says: "Research has consistently shown that when an offer is presented using drip pricing, consumers are more likely to make a purchase and less likely to shop around and compare prices" (CMA, evidence review). The CMA also says: "It's illegal to hide additional fees, taxes or other charges that the customer will have to pay until later in the purchase process (sometimes called 'drip pricing')", and that a business found to have broken the law could be "fined up to 10% of your turnover, or £300,000, whichever is greater" and "ordered to compensate affected customers" (CMA, price transparency summary, updated 7 January 2026).

This is part of our series on sale prices and urgency, checked. It reports what the evidence and the regulators say, with links to each source; it is not legal advice.

What the evidence says

Shoppers "have been shown to focus predominantly on the lower headline price and underestimate the total price of the offer", the review says (CMA, evidence review). We found no study of what it does for a small shop.

Can you do it legally?

Not with a fee customers cannot avoid, and showing it separately will not normally be enough. The total price "should normally include any unavoidable or 'mandatory' charges", and a charge is mandatory "if the customer must pay it to buy the product". That applies to the first price you show, including in "online marketing, like an email or a social media post". For a flat fee on each order: "Include mandatory per-transaction charges in the total price of the product, even in early-stage advertising." The exception is a charge you cannot work out in advance, such as a delivery charge that varies with the customer's location: then you must give the customer what they need to calculate the total, as prominently as the headline price. The CMA's examples "are not exhaustive and there may be other ways to comply with the law" (all from the CMA's summary).

What to do instead

• List every charge a customer cannot avoid. Each should normally be in the advertised price unless it cannot be worked out in advance.
• Check the sale adverts, not only the site. An illustration with made-up numbers: if the advert says £20 and every order carries a £2 fee, the advert should say £22.
• If you show a "was" and a "now" price, include the same fees in both; the comparison itself is covered in does a 'was' price make a sale sell better?

A sale that adds a countdown timer to the same checkout has a deadline to keep as well, and whether the rules reach a small business comes later in the series.

Rebuilding a checkout to show totals properly is part of our websites work; how much a website costs sets out the range.