The Filler Tax: Why ‘Only £5 Away From Free Delivery’ Usually Costs You More
Photo: Mikael Häggström, Attribution, via Wikimedia Commons
There’s a particular kind of retail maths that happens at 11pm with a phone in one hand and a brew going cold in the other. Your basket is £54. The free-delivery threshold is £60. The delivery charge is £4.99. The site helpfully suggests a £6 pair of socks, a £7 candle or a £9 “essential” you didn’t know you needed until 30 seconds ago. Suddenly you’re not buying what you came for. You’re buying your way out of a fee.
That’s the filler tax. And in 2026, with delivery charges creeping and minimum spends plastered across fashion, homeware and grocery checkouts, it’s worth running the numbers properly.
The £4.01 question
Free-delivery thresholds are not charity. They’re a nudge. Retailers know a chunk of shoppers will spend more than the delivery fee to avoid paying it. The trap is that the extra spend often buys something you value at far less than the fee you “saved”.
Take a simple example. Delivery is £3.99. You’re £8 short of the free-delivery minimum. You add an £8 item. On paper, you’ve avoided the £3.99 charge. In reality, you’ve swapped a £3.99 cost for an £8 cost. To break even, that £8 item needs to be worth at least £4.01 to you — not the imaginary value on the price tag, but the real value of having it in your home.
If it’s a pair of socks you’ll actually wear, fine. If it’s a scented candle you’ll put in a drawer and forget about, you haven’t saved £3.99. You’ve spent £4.01 more than you needed to.
The break-even rule is blunt: only pad the basket if the filler is something you’d have bought anyway, or if you genuinely value it at more than the delivery fee. “It’s only a fiver” is not a financial strategy.
Fashion: the £60 threshold and the £6 sock
Fashion is where the filler tax does its best work. A £60 free-delivery minimum on a £54 basket feels tantalisingly close. The suggested add-on is often cheap, cheerful and strategically placed: socks, hair clips, a canvas tote, a belt you’ll never thread through a loop.
Run the maths. You add £6 of socks to save £4.99 delivery. If those socks are worth £2 to you — because you’ve got a drawer full and these are just OK — you’ve lost £3 on the transaction. If they’re worth £6 because you actually needed socks, you’re quids in. The difference isn’t the price. It’s the usefulness.
There’s also the returns question. Padding the basket can make returns messier, especially if the filler is non-returnable or if you’re now hovering around a free-returns threshold that changes your behaviour. A £4.99 delivery charge is clean. A £6 filler item you resent is clutter with a receipt.
Homeware: the candle that costs more than postage
Homeware thresholds are often higher — £50, £75, sometimes £100 — and the filler suggestions are dangerously pleasant. A £7 candle. A £9 picture frame. A £12 “small treat” that matches nothing you own.
This is where the maths gets emotional. Homeware filler feels like a gift to your future self. But if you wouldn’t have bought the candle at £7 in a shop, it’s not a bargain because it helped you dodge a £4.99 fee. It’s a £7 candle you didn’t need, bought to solve a £4.99 problem.
A useful test: would you pay the delivery fee to not own this item? If the answer is yes, don’t add it. Pay the postage. Keep the shelf space.
Grocery: the £40 minimum and the £6 of crisps
Online grocery thresholds are a different beast because the filler is edible. A £40 minimum spend with a £3.99 delivery charge can push a £34 shop into “just add some crisps” territory. But grocery filler has a habit of being the stuff you eat because it’s there, not because you planned for it.
If you add £6 of snacks to save £3.99, you’ve spent £2.01 more than the delivery charge. That’s fine if the snacks replace a future shop. It’s not fine if they vanish before Tuesday and you’re back online on Thursday. The break-even rule still applies: the filler has to earn its place in the trolley, not just in the checkout algorithm.
When paying the postage is the sane option
Paying £3.99 delivery can feel like losing. But it’s often the cheapest choice on the page. If the filler is low-value, low-use or likely to be returned, the delivery fee is the smaller number. You’re not “wasting” £3.99. You’re paying for exactly what you want and nothing else.
A simple rule for the next checkout: if you’re adding something solely to hit the threshold, stop and ask what it’s actually worth to you. If that number is lower than the delivery fee, pay the fee. If it’s higher, add it. If you’re unsure, close the tab and come back in an hour. The threshold will still be there. The urge to pad usually won’t.
Free delivery isn’t free. It’s a trade. Sometimes it’s a good one. Often it’s just a £6 candle in disguise.
