Pay calculation in the UK: what employers get wrong and how to fix it
Working out what to pay someone sounds straightforward — until you factor in tax bands, National Insurance, the latest minimum wage rates, and the quirks of part-time or variable hours. This post walks through how pay calculation actually works in 2026, and the mistakes we see most often when businesses try to do it themselves.
Pay calculation sits at the heart of running a compliant, trusted business. Get it right and your employees are paid correctly, your HMRC obligations are met on time, and everyone moves on. Get it wrong and you’re dealing with disgruntled staff, potential employment tribunal risk, and an HMRC compliance notice you really didn’t want.
In our experience working with owner-managed businesses across Greater Manchester and beyond, pay calculation is one of those tasks that looks simple on the surface but hides a surprising amount of complexity. Minimum wage thresholds change, tax bands shift each April, and the rules around irregular hours or apprentices catch a lot of employers out.
This post is our practical take on how to approach payroll calculations correctly in 2026 — covering the key rates, the most common errors, and what a sensible payroll process actually looks like for a small business.
What pay calculation actually involves
At its core, pay calculation is the process of working from an employee’s contracted rate to the net amount that lands in their bank account. That journey involves several distinct steps, and each one needs to be right.
The starting point is gross pay — the full amount owed before any deductions. For salaried staff that’s straightforward; for hourly workers, it means multiplying hours worked by the appropriate rate, including any overtime. From gross pay, you subtract:
- Income tax via PAYE (Pay As You Earn)
- Employee National Insurance contributions
- Any pension contributions under auto-enrolment
- Any other agreed deductions (student loan repayments, salary sacrifice arrangements)
What’s left is net pay — the take-home amount. Separately, you also need to account for employer National Insurance, which is a cost to the business on top of gross pay rather than a deduction from the employee’s wage.
Most payroll software handles this automatically once the inputs are correct. The problems usually start when the inputs are wrong — an incorrect tax code, a missed wage rate update, or a contractual hours figure that doesn’t reflect reality. The calculation engine is reliable; the human data entry is where things go awry.
The 2026 minimum wage rates you need to know
From April 2026, the National Living Wage and National Minimum Wage rates increased again. If you haven’t updated your payroll records to reflect these, you’re likely underpaying staff — which is both a legal breach and, when HMRC investigates, a costly one to put right.
The current rates are:
- £12.71 per hour — National Living Wage, workers aged 21 and over
- £10.85 per hour — workers aged 18 to 20
- £8.00 per hour — workers under 18, and apprentices in their first year or aged under 19
That last point about apprentices trips people up regularly. An apprentice aged 19 or over who has completed their first year moves onto the standard age-appropriate rate — they don’t stay on the apprentice rate indefinitely. Failing to make that transition at the right point is a genuine compliance risk.
It’s also worth remembering that the minimum wage applies to basic pay only in most cases. Certain deductions — such as uniform costs or accommodation above the permitted offset rate — can bring effective hourly pay below the legal minimum even if the headline rate looks compliant. HMRC’s minimum wage checks look at effective pay, not just the contractual rate.
The payroll calculation itself is rarely the problem. The errors nearly always come from bad inputs — stale rates, wrong tax codes, or hours that were never properly recorded.
How income tax affects take-home pay
The PAYE system deducts income tax directly from an employee’s wages each pay period, spreading the annual tax bill across the year. For the 2026/27 tax year, the key thresholds are:
- Personal Allowance: £12,570 — no income tax on earnings up to this point
- Basic rate (20%): taxable income from £12,571 to £50,270
- Higher rate (40%): taxable income from £50,271 to £125,140
- Additional rate (45%): taxable income over £125,140
For employees earning over £100,000, the Personal Allowance tapers away — reducing by £1 for every £2 of income above that threshold, and disappearing entirely at £125,140. This creates an effective 60% marginal rate on income between £100,000 and £125,140, which is something higher-earning director-employees in particular need to be aware of.
Each employee has a tax code — usually starting with a number close to 1257 for standard allowances — that tells your payroll software how much of their pay to treat as tax-free. Wrong tax codes are one of the most common causes of employees either overpaying or underpaying tax across the year. If someone’s tax code looks unusual (letters like K, D0, or BR), it’s worth understanding why before you run payroll.
For a more detailed breakdown of what this means for take-home pay, our take home salary guide covers the numbers in plain English.
Where small businesses most often go wrong
Running payroll manually — or using a spreadsheet that hasn’t been updated since last April — is where the majority of errors originate. These aren’t always dramatic mistakes; they’re usually small, systematic ones that compound over time.
The most common issues we see:
Stale wage rates
Minimum wage rates change each April. It takes about five minutes to update payroll software and about twelve months to notice you forgot. Always review rates at the start of the new tax year.
Ignoring statutory payments
Statutory sick pay, statutory maternity pay, and similar obligations need to be calculated correctly and processed through payroll — not handled informally or estimated. They affect both the employee’s pay and your HMRC submissions.
Auto-enrolment drift
Pension contributions must be calculated on qualifying earnings, which have a lower and upper threshold. Applying the contribution rate to total gross pay instead of qualifying earnings produces the wrong figure — usually underpaying into the pension scheme.
Irregular hours not tracked properly
For hourly or zero-hours workers, the calculation is only as good as the timesheet data feeding into it. Inconsistent recording of hours — or rounding in the employer’s favour — is a common audit flag.
Automated payroll software removes most of these risks, but only if it’s set up correctly and reviewed each time something changes.
Our take
Pay calculation doesn’t have to be complicated, but it does have to be right. The combination of annual rate changes, individual tax codes, auto-enrolment rules, and variable hours means there are enough moving parts to catch even careful employers out.
Our recommendation to most small business owners is simple: use compliant payroll software, review your rates every April, and don’t treat payroll as something to set up once and forget. If you’re running payroll manually or haven’t reviewed your setup in a while, it’s worth a fresh look — especially now that the April 2026 minimum wage increase has come into effect.
If your payroll setup needs a review, or you’d like someone to handle it entirely, this is exactly the kind of thing we help clients with at Edward Harris. A quick conversation costs nothing.
Frequently asked questions
How do I calculate gross pay for an hourly paid employee?
Multiply the number of hours worked in the pay period by the employee’s hourly rate. If the employee worked overtime at a different rate, calculate that separately and add it to standard hours pay. The result is gross pay — before any tax, National Insurance, or pension deductions are applied.
What is the difference between gross pay and net pay?
Gross pay is the full amount an employee earns before any deductions. Net pay — often called take-home pay — is what remains after income tax, employee National Insurance, pension contributions, and any other deductions have been subtracted. Employer National Insurance is an additional cost to the business, not deducted from the employee’s gross pay.
How often do National Minimum Wage rates change?
National Minimum Wage and National Living Wage rates are reviewed annually and typically increase each April. From April 2026, the National Living Wage for workers aged 21 and over rose to £12.71 per hour. Employers must update their payroll records when new rates take effect — underpaying the minimum wage is a legal breach regardless of whether it was intentional.
What is a tax code and why does it matter for pay calculation?
A tax code tells your payroll software how much of an employee’s income to treat as tax-free before applying the correct income tax rate. Most employees on standard allowances will have a 1257L code, reflecting the £12,570 Personal Allowance for 2026/27. An incorrect tax code will result in the wrong amount of tax being deducted every pay period, creating either an underpayment or overpayment that HMRC will eventually need to correct.
Do I need payroll software or can I calculate pay manually?
Manual pay calculation is possible but carries a high risk of error, especially across multiple employees or where hours vary. Most HMRC-recognised payroll software handles tax and NI calculations automatically and submits Real Time Information (RTI) reports to HMRC. For most small businesses, the time saved and compliance assurance makes payroll software the more practical choice.