Your August payslip lower than July, with the same hours and no job change? Here are the five usual causes and the first things to check.
You opened your August payslip expecting roughly the same number as July, and it came in lower. Same hours, same job, no obvious reason. So what shrank?
Unlike April, August is not the start of a new tax year, so nothing resets automatically this month. That actually makes it easier to diagnose: when an August payslip is lower and nothing changed at work, the cause is almost always specific to you, and it usually sits in one of five places. Here is how to work through them in the order that finds the answer fastest.
Your take-home is gross pay minus deductions, so an August payslip lower than July means one of two things happened: you earned less before tax this month, or more was taken off the same gross. Everything below is just a way of finding out which.
The deduction that moves most often mid-year is income tax, and it moves because your tax code changed. Your tax code tells payroll how much of your pay to leave untaxed each period. Drop the code, and more of your pay becomes taxable straight away.
Here is a worked example. Say you earn £30,000 on the standard code 1257L, paid monthly. That protects £12,570 a year, about £1,047.50 a month, and leaves you with take-home of roughly £2,093 after 20% income tax and 8% National Insurance.
In July, HMRC finishes checking your 2025/26 tax and finds you underpaid by about £400, maybe from untaxed savings interest. Rather than send a bill, it collects the £400 by trimming your tax-free allowance for the rest of 2026/27. Your code drops, and the extra tax is spread across the remaining pay periods, which works out at around £50 more a month in this example.
Your gross pay is still £2,500. Your hours are identical. But your August take-home is now about £2,043 instead of £2,093, purely because the tax line went up. This is the single most common reason an August payslip is lower, and the only visible clue is the code printed near your name.
HMRC reconciles the previous tax year across the summer and into autumn, so June to November is peak season for codes to move. The triggers are a P800 underpayment being coded out, a new benefit in kind such as a company car or private medical cover, or a correction to your estimated income. A lower code means a smaller tax-free allowance and a bigger tax deduction from the same pay. My guide to tax code 1257L covers what the standard code looks like and how far yours has drifted from it.
If July carried a bonus, extra overtime, or a backdated pay award, it was inflated, and August simply returned to normal. There is a sting in the tail too. Because PAYE is cumulative, a one-off £1,000 bonus in July can be partly taxed at 40% in that month, so July looked great and the tax bill was quietly large. August, with no bonus, drops back to your usual take-home. The small month is the real one.
Public sector and NHS workers feel this most. Pay awards are often agreed mid-year and backdated, so a lump sum lands in one summer payslip, gets taxed heavily in that single period, and then every month after looks small next to it. If your July was unusually high, line it up against June rather than against August, and you will usually see that August is the normal number and July was the spike.
For anyone on variable hours, August is holiday season. If you took unpaid leave, picked up fewer shifts, or your sector slowed down over the school holidays, your gross fell and your take-home followed. Worth comparing the hours or shifts line on August against July before you blame anything else.
If you are paid every four weeks rather than monthly, you get 13 pay packets a year, not 12, and the gaps between paydays do not line up neatly with calendar months. Some months you are paid for fewer working days than others, which makes a payslip look smaller without anything actually changing. Weekly and four-weekly pay cycles drift against the months all year, and summer is when people tend to notice.
A few deductions can switch on mid-year. A pay rise can push you over the Plan 2 student loan threshold for the first time, and repayments are 9% of everything above it. Pension contributions can step up after an auto-enrolment review. Or you joined a salary sacrifice scheme for a pension, car, or cycle-to-work, which lowers your take-home now in exchange for a benefit. Each one is a deduction that was not there in July.
Work from the payslip outwards, in this order.
First, compare gross pay, July against August. If the gross dropped, the cause is hours, shifts, or leave, and it is between you and payroll. If the gross is identical but take-home fell, the change is in a deduction.
Second, read the deductions line by line. Tax, National Insurance, pension, student loan. Find the one that moved. National Insurance and tax both rise with gross pay, so a jump in tax on the same gross points straight at your tax code.
Third, check your tax code against HMRC. Log into the HMRC app or your Personal Tax Account, tap Pay As You Earn, and look for a recent P2 notice. That notice spells out exactly why your code changed and what it is recovering. If you want a walkthrough of confirming the code is right, the verify your tax code guide takes you through it.
Fourth, only then ring payroll, on the part they control. Payroll applies the code HMRC sends, they do not set it. So if your gross is wrong, that is a payroll conversation. If your code is wrong, that is an HMRC one, on 0300 200 3300.
The personal allowance is still £12,570 for the 2026/27 tax year. It has been frozen since 2021 and is scheduled to stay frozen through April 2028, so the standard code 1257L has not changed and no national rate change is making your August lower. If your code dropped below 1257L, the reason is specific to you.
The thing that did change, back in April 2026, is how HMRC tells you. Most P2 coding notices are now digital-first, so instead of a letter in the post your code update lands in your HMRC online account or app. That is why plenty of people see their take-home move mid-year with no warning: the notification is easy to miss. If your August payslip dropped and you never saw a letter, the explanation is almost certainly sitting in your HMRC account right now.
For variable-income workers, none of the underlying rules shifted over the summer either. The 8% National Insurance rate and the £12,570 threshold are unchanged, so a smaller August is about your hours or your code, not a new deduction the government quietly introduced.
If you want to see what your take-home should be this month at your hours or salary, the NetPay app runs the full calculation for you, including income tax, National Insurance, pension, and student loan, so you can spot the moment a payslip does not add up. Free to download.
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The most common reason is a mid-year tax code change. HMRC runs its reconciliation of the previous tax year over the summer, and if you underpaid tax or picked up a taxable benefit, your code drops and your take-home falls. The other big one is that July was inflated by a bonus, overtime, or a backdated pay award, so August only looks small by comparison. Check the HMRC app first to see whether your code moved.
Yes. HMRC can reissue your tax code at any point, not just in April. Mid-year changes usually follow a P800 reconciliation, a new benefit in kind like a company car, or a correction to your estimated income. You will see the new code on your payslip and, if you look, a P2 notice in your HMRC online account explaining it.
PAYE is cumulative, so a bonus is added on top of your normal pay for that month and a chunk of it can be taxed at 40% even if your salary is usually in the 20% band. The following month, with no bonus, your pay drops back and so does your take-home. Nothing is wrong, the big month was the outlier, not the small one.
Check three things first: your tax code, your gross pay versus last month, and your deductions line by line. If the gross is the same but the tax jumped, the cause is almost certainly your tax code, which HMRC sets, not payroll. Only ring payroll once you know whether the change is in the gross pay they control or the code HMRC sent them.
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NetPay UK works out your real net pay after tax, NI, pension and salary sacrifice, for hourly, shift and variable-income workers. Free to download.
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A note on financial advice: NetPay UK calculates take-home pay based on official HMRC tax rules. This article reflects rules in force at the time of publication (29 June 2026). Tax rules change. For complex situations, consult a qualified UK accountant or visit gov.uk/income-tax.
