How Average Weekly Earnings Are Worked Out for SMP
Everything about your Statutory Maternity Pay comes out of one number: your average weekly earnings. It decides whether you qualify at all, it sets the first six weeks, and it can cap the remaining thirty-three.
It is also the number employers most often calculate wrongly, usually by using the wrong eight weeks. This page works through the definition properly, with examples, using the figures for 2026/27. It is general information rather than advice on your own pay.
Start with the qualifying week
Everything is anchored to the qualifying week, which is the 15th week before the week your baby is due.
To get SMP you need to have been continuously employed by the same employer for at least 26 weeks up to any day in that week. So the practical test is: count back 15 weeks from your expected week of childbirth, and ask whether you had been there six months by then.
The qualifying week also sets the end of the period your earnings are averaged over, which is the next piece.
The relevant period
Your average weekly earnings are worked out over the relevant period, and this is the part that gets muddled.
The relevant period ends on the last normal payday on or before the Saturday of the qualifying week. It starts the day after the last normal payday falling at least eight weeks before that end date.
Two things follow. It is built from paydays rather than from calendar weeks, so it will not line up neatly with the qualifying week itself. And it is roughly eight weeks long, which for a monthly-paid employee means it typically covers two monthly paydays.
The single most common error. Payroll uses the eight weeks before maternity leave starts, rather than the eight weeks before the qualifying week. Those can be four or five months apart, and if your pay changed in between, the two produce completely different answers.
The Arithmetic
Paid weekly: add up the gross pay in the relevant period and divide by 8.
Paid monthly: add up the gross pay in the relevant period, divide by the number of months in it (usually 2), multiply by 12, then divide by 52.
Gross means before tax and National Insurance. It includes overtime, commission, bonuses and back pay, provided they were actually paid within the relevant period. It is the money paid in that window, not the money earned in it.
What the figure then buys you
| Period | What you receive in 2026/27 |
|---|---|
| Weeks 1 to 6 | 90% of average weekly earnings, with no upper limit |
| Weeks 7 to 39 | £194.32, or 90% of average weekly earnings, whichever is lower |
| Weeks 40 to 52 | Nothing, unless your employer has an enhanced scheme |
You also need average weekly earnings of at least £129, the Lower Earnings Limit for 2026/27, to qualify for SMP at all. Below that, SMP is not payable and Maternity Allowance becomes the route to look at.
One thing worth noting: some GOV.UK pages still show £125, the 2025/26 figure, because not every page is updated at the same time. The employer rates and thresholds guidance for 2026 to 2027 gives £129.
Worked example: monthly paid
Your baby is due in the week beginning Sunday 15 November 2026. Counting back 15 weeks, the qualifying week begins Sunday 2 August 2026, and its Saturday is 8 August.
You are paid on the 28th of each month. The last normal payday on or before 8 August is 28 July. The last payday at least eight weeks before that is 28 May, so the relevant period runs from 29 May to 28 July, covering the June and July paydays.
Gross pay was £2,400 in June and £2,650 in July, the second including a £250 bonus. Total £5,050.
£5,050 ÷ 2 = £2,525. × 12 = £30,300. ÷ 52 = £582.69 average weekly earnings.
First six weeks: 90% of £582.69 = £524.42 a week. Weeks 7 to 39: 90% is still well above the standard rate, so £194.32 a week.
Total SMP: (6 × £524.42) + (33 × £194.32) = £3,146.52 + £6,412.56 = £9,559.08 gross across 39 weeks.
Notice how much that bonus was worth. Because it landed inside the relevant period, it lifted average weekly earnings by about £29, which added roughly £155 across the first six weeks. A bonus paid a month later would have been worth nothing at all for SMP purposes.
Worked example: weekly paid, part-time
You are paid every Friday. The last Friday on or before the Saturday of your qualifying week is 7 August 2026, and eight weeks before takes the relevant period back to 13 June.
Gross pay across those eight weeks was £168, £210, £168, £0, £196, £168, £224 and £182. Total £1,316.
£1,316 ÷ 8 = £164.50 average weekly earnings. That is above £129, so SMP is payable.
First six weeks: 90% of £164.50 = £148.05 a week. Weeks 7 to 39: 90% of earnings is £148.05, which is lower than £194.32, so you receive £148.05 a week throughout.
This is the pattern for lower earners. Where 90% of your earnings is below the standard rate, the standard rate never applies and every week is at the same figure.
The week you took unpaid leave
In that second example, one week had zero pay. It still divides into the total, which pulls the average down.
If you have a choice about when to take unpaid leave, unpaid sick leave, or a career break, keeping it out of the relevant period protects your SMP. That is not always possible, but it is worth knowing the window exists, because most people have no idea their SMP is being decided by eight specific weeks several months before their leave starts.
Salary Sacrifice
Salary sacrifice arrangements, for pension contributions, a cycle scheme or a car, reduce your gross pay. Average weekly earnings are based on gross pay actually paid, so a sacrifice inside the relevant period reduces the figure and therefore reduces your SMP.
The effect can be significant on the first six weeks, which are uncapped and paid at 90%. If you have any flexibility about when a sacrifice arrangement starts or how much is sacrificed, that is worth reviewing well before the qualifying week.
Non-cash benefits provided through salary sacrifice generally have to continue during maternity leave, because they are a benefit rather than pay, and statutory pay itself cannot be reduced by a sacrifice. The interaction is genuinely technical, so ask your employer to set out in writing what will happen to each arrangement during your leave rather than working it out from the handbook.
Pay Rises
There is a long-standing rule that a pay rise taking effect between the start of the relevant period and the end of maternity leave should be reflected in SMP, with average weekly earnings recalculated as though the higher rate had applied throughout the relevant period. It comes from a case brought against an employer that had not done so.
The point of it is that a backdated or mid-leave rise should not pass you by simply because your earnings were averaged before it happened. Employers do not always apply it automatically, so if you received a rise at any point in that window, raise it and ask for the recalculation in writing. This is one to confirm with your payroll team or HMRC for your own circumstances rather than assume.
Checking your own figure
Work through it in this order.
- Find your expected week of childbirth and count back 15 weeks to the qualifying week
- Find the Saturday of that week
- Find the last normal payday on or before it
- Count back to the last payday at least eight weeks earlier
- Add the gross pay between those two points
- Apply the weekly or monthly formula
The SMP calculator on this site will do the arithmetic once you have the dates. If your figure and payroll's figure disagree, ask them which two paydays they used, because that single question resolves most of these.
If an employer decides you do not qualify, they must give you form SMP1 setting out why, normally within seven days of the decision. Get it, because you need it to claim Maternity Allowance instead, and because it puts their reasoning in writing where you can check it.