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Most guidance on the calculation of commission on sales stops at rate × revenue. That part has never been the problem. UK sales orgs don't overpay because somebody multiplied badly — they overpay because the number got multiplied against the wrong base, at the wrong point in the deal's life, in the wrong order relative to tiers, splits and caps. The arithmetic is secondary. The sequence is everything.
TL;DR
The calculation of commission on sales has four moving parts: the base you pay on, the rate structure, the measurement period, and the adjustments (splits, caps, clawbacks, ramp). The single biggest source of UK overpayments is paying on the gross signing-day contract value rather than the value actually locked in once opt-out, ramp and cancellation clauses are accounted for. Commission is ordinary earnings: HMRC's guidance on bonuses confirms cash bonuses and commission are added to other earnings with PAYE and Class 1 National Insurance deducted through payroll, and HMRC's National Insurance Manual (NIM08600) confirms such payments fall into the earnings period in which they are paid. For 2026/27, employer secondary Class 1 NICs run at 15% on earnings above the £5,000 secondary threshold, so every £1,000 of commission costs the employer £1,150. Calculate against the contract, not the CRM headline, and publish the working before payroll runs.
What does the calculation of commission on sales actually involve?
The calculation of commission on sales is the process of converting a closed deal into a gross payroll amount, defensibly. Four inputs decide the answer: the commissionable base (what portion of the deal value counts), the rate structure (flat, tiered, accelerated), the measurement period (monthly, quarterly, annual-to-date), and the adjustments layered on top (desk splits, caps, ramp, clawback).
UK teams generally pick one of two method families, and they produce different numbers from identical deals.
| Method | How it works | Best for | Where it breaks |
|---|---|---|---|
| Revenue-rate | A percentage of commissionable revenue, e.g. 2.5% of new ARR | Transactional teams, recruitment desks, high deal counts | Rewards volume regardless of quota; weak signal when territories differ wildly |
| Quota-attainment | Pay a percentage of the rep's target variable based on % of quota hit | Teams with reliable, differentiated quotas | Useless if quotas are set badly — a soft quota mints accelerators |
Neither is "correct". Revenue-rate is simpler to explain and easier to audit; attainment-based plans communicate priority better but inherit every flaw in your quota-setting. Pick the one your data can actually support, then stop re-litigating it mid-year.
Which base should you calculate commission on?
The commissionable base is where real money gets lost. A deal's signing-day headline — total contract value in the CRM — is a marketing number, not a committed one. If the contract carries a 90-day opt-out, a ramped first year, or a cancellation right, the amount legally locked in on signing day is smaller than the figure the rep is celebrating.
In practice, the root cause of most UK clawback fights is Finance paying on gross total contract value in a rush to hit the payroll cut-off, before the deal's opt-out window has closed. Commission should be calculated on the value actually locked in — not the signing-day headline — whenever a deal carries opt-out, ramp or cancellation clauses. That is a calculation decision, not a policy decision, and it has to be made before the first payout, not after the first reversal.
Pay on what the contract commits to, not on what the CRM celebrates.
The related choice — gross revenue, net revenue, gross margin or invoiced value — is a separate decision we unpack in commission paid on sales: gross margin, net revenue or invoice value. Whatever you choose, write the definition into the plan document in a sentence a rep can read in ten seconds.
What is the correct order of operations?
Commission mechanics are not commutative. Applying a cap before a split gives a different answer from applying a split before a cap. Run the same six steps in the same order, every period.
- Establish the commissionable base per deal. Strip out VAT, pass-through costs, and any portion not yet contractually locked in. Record the figure you used and why.
- Apply splits first, at deal level. If two reps share a deal 50/50, each rep's attainment should be built from their share — not from the whole deal with a haircut at the end.
- Roll up to period attainment. Sum each rep's share against the quota for the measurement period. Decide in advance whether attainment is period-only or annual-to-date, because accelerators behave very differently under each.
- Apply the rate structure in bands. Base rate up to quota, then any accelerator or decelerator band above or below. Never apply the top rate retrospectively to the whole number unless the plan explicitly says so.
- Apply adjustments. Caps, ramp protections, draw recovery, and any clawback or rebate due from a prior period under your clawback policy.
- Convert to a gross payroll line and cost it. Add employer NICs, check the figure against the contract terms, then release to payroll.
A worked example: £186,000 closed, £4,087.50 earned
Take a UK account executive on a £45,000 base and £15,000 variable at 100% attainment — an OTE of £60,000 on a 75/25 split — carrying a £600,000 annual new-ARR quota measured quarterly. The base rate is £15,000 ÷ £600,000 = 2.5% of commissionable revenue, with a 1.5× accelerator (3.75%) above the £150,000 quarterly quota.
Q3 closes with four deals:
| Deal | Signing-day TCV | Locked-in value | Note |
|---|---|---|---|
| A | £60,000 | £60,000 | 12-month term, no break clause |
| B | £48,000 | £48,000 | Clean |
| C | £42,000 | £42,000 | Clean |
| D | £36,000 | £9,000 | 3-month opt-out; only quarter one committed |
| Total | £186,000 | £159,000 |
Calculated on the signing-day headline: £150,000 × 2.5% = £3,750, plus £36,000 above quota × 3.75% = £1,350. Payout £5,100.
Calculated on locked-in value: £150,000 × 2.5% = £3,750, plus £9,000 above quota × 3.75% = £337.50. Payout £4,087.50.
The gap is £1,012.50 on a single quarter, for one rep, from one clause nobody read. If the customer exercises the opt-out, that £1,012.50 becomes a clawback — and the employer has also paid 15% employer NIC on it (£151.88) that now needs unwinding through a payroll correction. Multiply by eight reps and the cost of the wrong base is a four-figure problem every quarter.
Notice that the entire error landed in the accelerated band. Because accelerators apply to the marginal pound, any overstatement of the base is paid at the highest rate in the plan. A 20% overstatement of revenue produced a 25% overstatement of commission here. Getting the base right matters most precisely where reps are watching hardest.
What does commission actually cost the employer?
The gross commission figure is not the cost. Commission is earnings, so three further layers attach to it.
First, payroll deductions. HMRC's guidance on bonuses states that a cash bonus counts as earnings and must be added to the employee's other earnings with PAYE tax and Class 1 National Insurance deducted through payroll — commission is treated the same way. HMRC's National Insurance Manual at NIM08600 confirms that one-off payments such as bonuses and commissions form part of gross pay in the earnings period in which the employer pays them — they "lie where they fall" — which is why a single large quarterly payout can push a rep through NIC bands in one month.
Second, employer NICs. According to HMRC's rates and thresholds for employers 2026 to 2027, employer secondary Class 1 NICs are charged at 15% on earnings above the secondary threshold of £5,000 a year (£417 a month). A rep on a £45,000 base is already well above that, so the £5,100 payout in the worked example costs the employer £5,865 before anything else. We break the budgeting maths down further in the employer NIC cost of commission.
Third, holiday pay. Acas guidance on commission when employees are off work states that employers must include payments linked to doing required contractual tasks — including commission — in at least four weeks of holiday pay. That is an additional cost on top of the commission itself, and it is routinely missing from commission budgets. See holiday pay on commission for the reference-period mechanics.
Who should check the calculation before payroll runs?
The sales manager — before Finance sends it, not after. Protecting a sales team isn't only about helping them close; it's about shielding them from internal operational mistakes. Sanity-check the commission calculation against the real contract terms before payroll runs, because once a wrong number has been paid, the correction is what does the cultural damage.
That is also why disputes are a visibility problem rather than an accuracy problem. Reps don't lose faith because a number is occasionally wrong — they lose it when they can't see how it was built and a correction lands with no warning. A calculation that shows its working, deal by deal, prevents more arguments than a cleverer plan ever will. If you're still reconciling in Excel, the related read is why most commission calculators break.
Frequently asked questions
Should commission be calculated on invoiced revenue or booked revenue?
It depends on your cash risk. Calculating on invoiced or collected revenue protects the business from non-payment but delays reward and demotivates reps on long payment terms; calculating on bookings pays faster but exposes you to clawbacks. A common middle path is to calculate on bookings and pay on a locked-in basis, releasing accelerated portions once the opt-out or rebate window has closed.
Is commission taxed differently from salary in the UK?
No. HMRC guidance on bonuses confirms cash bonuses count as earnings, with PAYE and Class 1 National Insurance deducted through payroll, and commission is treated the same way. The reason a commission month looks oddly taxed on a payslip is timing, not a different rate — NIM08600 confirms such payments fall into the earnings period in which they are paid.
How do you calculate commission when two reps share a deal?
Apply the split at deal level before rolling up attainment, so each rep's quota progress reflects only their share. Splitting after the commission has been calculated on the whole deal produces different — usually higher — results once accelerators are involved, and it is one of the most common causes of quarter-end disputes.
Does commission count towards holiday pay calculations?
Yes, for at least part of statutory leave. Acas guidance states that employers must include payments linked to required contractual tasks, including commission, in at least four weeks of holiday pay, with the remaining 1.6 weeks able to be paid at basic rate.
How often should commission be calculated?
At the same cadence you pay, with a visible running figure in between. Monthly or quarterly payout cycles are standard in UK sales orgs, but reps should be able to see their in-period calculation continuously — waiting until the payroll cut-off to reveal the number is what turns a small error into a formal dispute.
Before your next payroll cut-off
If the calculation of commission on sales in your business currently lives in a spreadsheet that one person rebuilds every quarter, the £1,012.50 gap in the worked example above is not hypothetical — it is the shape of the error you will eventually find, usually after it has been paid, and usually with 15% employer NIC attached to it. Commit's 14-day free trial calculates commission directly from HubSpot deals, pays it through Xero payroll, and keeps a full audit trail of how every figure was built, so the manager check happens before payroll rather than after the apology. Run it against one real quarter of your own plan and see which numbers disagree with your sheet.
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