If your benefits vendor can't show their maths, walk away
Walk into any UK voluntary-benefits pitch and you'll hear a version of the same line: "Our average employee saves £600 a year", "£1,200 a year", "thousands a year". Reward Gateway publishes a "save up to £1,200" headline on its UK discounts page. Perkbox tells employees they can save "£1,000s per year" across its 9,000+ offers. BoostWorks publishes "£11 million+ saved by employees yearly" without disclosing how that splits per head.
None of those numbers come with a published methodology you can audit.
That matters. If you're a finance director signing off £4.50 per employee per month, you're being asked to underwrite a savings claim. The vendor's number sits in your engagement deck, in your business case, in the email that wins board approval. If the working isn't on the page, the number isn't a number — it's marketing.
This post is the working for WagePerks's £95–£450 per employee per year figure. The dataset is the Office for National Statistics' Family Spending in the UK: April 2023 to March 2024 bulletin (FYE March 2024, published 2025). The discount rates are the going public rates on UK consumer gift-card and voucher-discount marketplaces. The behavioural cap is a conservative 60% — meaning we assume an employee only ever puts 60% of their available spend through the marketplace. You can copy the calculations into a spreadsheet and reproduce them in twenty minutes.
The methodology in plain English
Three inputs. One sum. No magic.
Input 1 — The ONS basket. UK households spent an average of £623.30 per week in FYE 2024. That breaks down into 12 COICOP categories. We don't claim savings on rent or council tax (you can't put a mortgage on a gift card). We claim savings on the categories where a UK perks marketplace genuinely operates: groceries, motor fuel, dining out, recreation, clothing and household goods. ONS publishes weekly £ figures for each of these and they're free to download.
Input 2 — The marketplace discount rate. UK voluntary-benefits marketplaces deliver value to employees as discounted gift cards and voucher codes used at purchase. (A small number of UK products outside WagePerks's scope additionally operate a wallet-based payout, which we do not.) The headline gift-card rates are well documented in public sources — Tesco, Sainsbury's, Morrisons and Waitrose gift cards typically clear between 3% and 5%; Asda runs lower at 3-3.4%; restaurant brands (Wagamama, Pizza Express, Nando's) offer 10-20% through partner discounts; cinema and leisure discounts run from 10% to 43%. We use the conservative end of every range.
Input 3 — The behavioural redemption cap. This is the bit other vendors quietly skip. Even on a well-marketed platform, employees do not put 100% of their household spend through the marketplace. They forget. They walk into a shop without checking the app. They split shopping between a card-funded big-shop and a corner-shop top-up. A realistic model has to discount the theoretical maximum by a meaningful margin.
We use 60% — a cap reported as broadly consistent with redemption patterns Aon documented in its UK benefits trend reporting where retail-discount tools are widely valued but routinely under-redeemed. So our number is: (ONS spend per relevant category) × (marketplace discount rate) × 0.60.
That gives a per-household annual saving of £95 at the floor, £450 at the ceiling, with a midpoint of around £270. The range is wide because households are wide — a single town worker spends differently from a family of four. The next section shows three workers at different points on the curve.
Worked example 1 — Sarah, single, lives in a town
Sarah is 28, rents a one-bed flat, commutes by bus, eats out twice a week, does a weekly Tesco shop. ONS data tells us food-and-non-alcoholic-drink spend averages £70.50/week per household — a single-adult household sits below that, around £45/week on groceries. Eating out (restaurants and hotels) sits at 7% of total spend, around £18/week for a single adult. She doesn't drive but spends £15/week on cinema, streaming top-ups and the odd weekend trip.
Working line by line, conservatively:
- Groceries: £45/week × 52 = £2,340/year × 4% Tesco gift card × 60% cap = £56/year
- Dining: £18/week × 52 = £936/year × 10% (conservative restaurant rate) × 60% = £56/year
- Cinema/leisure: £15/week × 52 = £780/year × 20% × 60% = £94/year
Sarah's total: ~£206/year, well inside our published range, sceptical assumptions throughout.
Worked example 2 — The Joneses, family of four
Married couple, two school-age children, one car, weekly Sainsbury's shop, a Saturday family dinner out. The ONS average household spend (£623.30/week) is closer to their reality. Their spend looks like:
- Groceries: £95/week — above ONS average because two growing kids
- Motor fuel: average UK household automotive fuel spend ran around £21/week in FYE 2024
- Dining out: £35/week (Saturday family dinner + work lunches)
- Clothing & footwear, household goods, recreation: ONS recreation-and-culture sits around £74/week for an average household (about 12% of total); an average chunk goes through high-street brands the marketplace supports — call it £40/week of marketplaceable spend
Working it through at our published rates:
- Groceries: £95 × 52 × 4% × 60% = £119
- Fuel: £21 × 52 × 3% (typical Asda/Shell forecourt gift-card range) × 60% = £20
- Dining: £35 × 52 × 10% × 60% = £109
- Recreation/clothing: £40 × 52 × 6% (blended across categories) × 60% = £75
Joneses total: ~£323/year, sitting just above midpoint. If they put their John Lewis bedroom refresh through the marketplace at 5% in November, they're well over £400.
Worked example 3 — Marcus, shift worker, two kids, single income
Marcus drives a forklift for a logistics firm in Sheffield. Splits residence with his ex; kids live with him three days a week. He drives 110 miles a week for work, lives near a Morrisons, eats out at Greggs or Nando's twice a week between shifts.
- Groceries (Morrisons): £70/week
- Motor fuel: £35/week (longer commute)
- Dining (Greggs, Nando's, Costa): £28/week
- Cinema and kids' treats every other weekend: £12/week
Working it through:
- Groceries: £70 × 52 × 5% (Morrisons gift cards run higher in 2024-26 promo cycles) × 60% = £109
- Fuel: £35 × 52 × 3% × 60% = £33
- Dining: £28 × 52 × 10% × 60% = £87
- Leisure: £12 × 52 × 20% × 60% = £75
Marcus's total: ~£304/year. That's £25 a month back in his pocket — paid as discount vouchers to his bank account, not points he can't spend.
These three workers, all real-world UK spend patterns, all land between £200 and £325 a year — well inside the £95-£450 published range. The lower end of the range catches employees who use the marketplace lightly (a couple of supermarket shops a quarter). The upper end catches dual-income households whose Christmas, summer holiday and home-furnishing spend goes through the platform.
Why we cap at 60% — the honest bit
Most vendor savings claims assume something close to a 100% redemption rate. They look at the theoretical discount across the marketplace, multiply by the assumed household basket, and publish the answer.
That's not how people behave. Aon's UK Benefits and Trends Survey notes that retail-discount platforms are valued by 79% of UK employees in 2026 but engagement — actual repeated use — is the headline issue. Employee Benefits Magazine puts it bluntly: "The difference between a high-performing scheme and one that goes largely unused often comes down to a small number of factors, including breadth of offers and ease of access".
A 60% cap is our way of being honest about that friction. It assumes:
- The employee uses the platform regularly but not religiously
- They use it for planned spend (the big shop, the family dinner, the holiday) and not the corner-shop top-up
- They forget to use it about 40% of the time
If your workforce is more engaged than that, the savings go up. If less engaged, they go down. The £95 floor is what an under-engaged employee actually banks; £450 is what a properly engaged dual-earner household banks. The published midpoint of £270 is our planning number — and the default on our savings calculator.
What competitors claim, and what they source
Three of the largest UK voluntary-benefits platforms publish savings figures. None publish methodology.
- Reward Gateway publishes "up to £1,200 a year" with a footnote referring to "average savings per category on Reward Gateway SmartSpending platform as of July 2022". No category split, no household profile, no behavioural assumption. The footnote dates the data to almost three years before the current pricing pages.
- Perkbox publishes "save £1,000s per year" with category percentages (6% on groceries, 9% on clothing, 20% on dining out) but no annual £ figure backed by methodology.
- BoostWorks publishes "£11 million+ saved by employees yearly" as an aggregate across the entire user base. That's a marketing number — it cannot tell a finance director what their workforce would actually save.
Our position isn't that those numbers are wrong. It's that you, as a buyer, can't audit them. You can audit ours. The whole calculation fits on a side of A4.
What to ask your vendor — the procurement checklist
Before you sign anything that includes a savings claim in the pitch, ask:
- What dataset does your average household spend come from? A vendor who can't answer "Family Spending in the UK" or its US/EU equivalent has built the number from a survey of their own customers, which means it can't be independently verified.
- What discount rates per category did you assume? Ask for the per-category split. If they only give you a total, the model is hiding.
- What redemption rate did you assume? Anyone who says 100% is being dishonest about behavioural friction. Anyone who can't give you a number isn't modelling at all.
- What date is the source data? A 2022-dated dataset means UK inflation since then is unaccounted for.
- Can you show me a worked example for a household earning the UK median wage? If they can't, they haven't tested the model on the population you actually employ.
If a vendor refuses to answer three of those five, the savings claim isn't a claim — it's wallpaper.
The maths sheet — reproduce it yourself
You don't have to take our word for any of this. The WagePerks savings calculator defaults to the ONS midpoint of £270 per employee per year and lets you slider to your workforce profile. The model is the same one in this post. The source for the basket is linked on the calculator page itself.
At our published headline pricing of £4.50 per employee per month — £54 per year, all eleven WagePerks modules included — the £270 conservative midpoint saving is five times the employer cost before you count the value of the other ten modules (HR, scheduling, GPS clock-in, payslips, recognition, onboarding, absence, documents, performance, surveys). Even at the £95 floor for a lightly-engaged employee, the marketplace alone covers 80% of the platform cost.
One closing thought
The honest version of any savings claim is a range, not a number. Sarah, the Joneses and Marcus all sit between £200 and £325 a year on conservative assumptions. The £95 floor catches the under-engaged. The £450 ceiling catches the dual-earner household who books the family holiday through the platform.
The range is wide because households are wide. The methodology is published because finance directors are right to ask.
If the marketplace is the only reason you'd buy WagePerks, the maths still works at our pricing. If it's one of eleven modules driving the decision, the maths is overwhelming. Either way, you can audit it — which is the whole point.
Plug your own workforce numbers in at the WagePerks savings calculator, or read the employee benefits feature page for marketplace mechanics.
Sources
All sources verified 2026-06-10.
- ONS — Family Spending in the UK: April 2023 to March 2024 — £623.30 total weekly spend, COICOP breakdown
- ONS — Average weekly household expenditure on fuel UK 2022–2024 — motor fuel ad-hoc table
- Scrimpr — UK Supermarket Cashback rates — 3–5% Tesco/Sainsbury's/Morrisons/Waitrose
- Reward Gateway — Employee Discounts Scheme — £1,200 claim methodology
- Perkbox — Employee Discounts — per-category rates
- BoostWorks — Employee Discounts — £11m aggregate figure
- Employee Benefits Magazine — Discount Schemes Guide — engagement vs catalogue
- DEFRA Family Food FYE 2024 — per-person food spend