Open an online Self Assessment return this filing season and, for a lot of people, there's already a number sitting in the Child Benefit box. HMRC put it there, and the return works the High Income Child Benefit Charge out from it. The arithmetic will be more reliable than mine.
The declaration at the bottom hasn't changed a word. It still says the information given is correct and complete, and the name under it is still yours.
TL;DR: HMRC now pre-fills Child Benefit figures in around 300,000 online Self Assessment returns and calculates the High Income Child Benefit Charge automatically. The tax itself is unchanged; what's new is who typed the number. You still sign the declaration, so check the figure against the bank rather than against what looks about right.
What Has Actually Changed in Your Tax Return?
This is a change to the mechanics. HMRC has switched on pre-population of Child Benefit information inside the online return, using payment data it already holds, so the charge is calculated for you. Around 300,000 Self Assessment customers will see their own or their partner's Child Benefit payments pre-populated (HMRC Agent Update issue 146, 2026). That's the 2025-26 return, due online by 31 January 2027.
Everything about the charge itself stands where it did. It bites once adjusted net income passes £60,000, claws back 1% of the Child Benefit for every £200 of income above that, and takes the lot at £80,000. Where a couple lives together, the higher earner pays (GOV.UK).
Worth separating from the data-matching story in HMRC's card takings work, where HMRC data checks your return after filing. This lands earlier, inside the return itself.
Why Does a Pre-Filled Number Need More Checking?
Because HMRC's record can be entirely accurate about the payments it made and still be the wrong figure for your return. The department knows what it paid out. The story around the claim sits outside its records.
The cases I'd look at hardest are the ones where the year wasn't clean:
- Payments that stopped part-way through the year
- A claim held in the other partner's name, or a partner who separated mid-year
- A child who aged out, or left approved education
- A high-income opt-out, where the claim was kept alive purely for the National Insurance credit but the payments were declined
That last one is common. As at August 2025, 685,000 families had opted out of receiving payments, covering around one million children (HMRC Child Benefit Statistics). Those claims sit on HMRC's system without money moving.
Check the number against what actually reached the bank account. A pre-filled figure carries an authority a blank box never had, and that's where the risk sits: people accept it. Very few will ever query a number that arrived looking official.
What Happens If You Override the Figure
HMRC's wording on overrides is short and easy to skim past: where pre-populated figures are displayed, you can amend them if you believe they are incorrect, but if you do, an explanation must be provided. Where HMRC doesn't hold all the payment information, the section still has to be completed by hand.
Read that as a change in working practice. You need the evidence supporting an override ready before you file, not assembled later when someone asks: the bank statement, the date payments stopped, the letter confirming the opt-out.
That habit is the one thing a year in audit drills into you. Write the note when you make the change, while you still remember why.
Who Is Liable if the Pre-Filled Figure Is Wrong?
You are. Pre-population moves the typing and leaves the responsibility with you, and the penalty regime has no category for "HMRC suggested it".
Penalties for inaccuracies run off behaviour under Schedule 24 of the Finance Act 2007. A careless inaccuracy carries up to 30% of the extra tax, reduced to nothing on an unprompted disclosure of good quality, or to a floor of 15% if HMRC prompted you first. Deliberate inaccuracies carry up to 70%. I've written before about where HMRC draws those lines.
The defence is where this matters. If you took reasonable care and the return was still wrong, there's no penalty at all. Reasonable care now quietly includes checking a number HMRC generated, which is where I expect the first arguments to land.
Can You Still Plan the Charge Away?
Yes, and automation makes this easy to forget. The charge keys off adjusted net income, one of the few figures an owner-manager can genuinely steer. Pension contributions and Gift Aid both reduce it, and both are grossed up: every £1 you pay into a relief-at-source pension takes £1.25 off the calculation (GOV.UK).
A worked example
Take a director in the current 2026-27 year, the one you can still influence, with adjusted net income of £70,000 and two children. At this year's rates of £27.05 a week for the eldest and £17.90 for the second (GOV.UK), the family receives £2,337.40 across the year. Being £10,000 over the threshold means a 50% clawback, and because the legislation rounds down to whole pounds, the charge comes out at £1,168.
Pay £8,000 into a relief-at-source pension and the scheme grosses it to £10,000. Adjusted net income drops to £60,000, the charge disappears, and there's a further £2,000 of higher-rate relief to claim through the return. Eight thousand pounds out of the current account puts £10,000 in the pension and removes £1,168 of tax.
The timing is unforgiving. A contribution only counts against a tax year if it lands by 5 April, so it's a decision you make before the year ends, not while filling in the return. The salary and dividend split moves the same number, and the contribution rules shifted this year, so run this year's figures before you commit to an amount.
Doing the arithmetic isn't the same as advising on the inputs. The machine will compute the charge faster and more accurately than either of us. It can't tell you the number should have been smaller.
The PAYE Route That Skips the Return Entirely
Some people filing this year don't need to. Since September 2025 there's been a service that collects the charge through your PAYE tax code instead, aimed at people whose only reason for filing is the Child Benefit charge.
One trap sits in the handover. If you've previously filed under Self Assessment, HMRC won't remove you automatically. You have to de-register first, then use the service the following day (ICAEW). ICAEW also reports HMRC writing to around 100,000 individuals who look liable to the charge but aren't in Self Assessment at all.
The window is the same 31 January that ends the filing season, so leaving it late means doing both jobs at once. For anyone with self-employment, rental income or dividends, the return is happening anyway. For a salaried director with a straightforward year, it's worth ten minutes.
Frequently Asked Questions
If HMRC pre-fills my Child Benefit figure and it is wrong, who is liable?
You are. The pre-populated figure is HMRC's suggestion based on the data it holds, and the declaration you sign covers the whole return. If the figure is wrong and you accept it, the inaccuracy is yours. Taking reasonable care to check it is what protects you from a penalty.
How do I work out my adjusted net income?
Start with total taxable income before the personal allowance, then deduct grossed-up Gift Aid donations and grossed-up relief-at-source pension contributions, plus pension payments made gross and trading losses. Every £1 of qualifying contribution reduces the figure by £1.25.
Can a pension contribution reduce or remove the High Income Child Benefit Charge?
It can, if it brings adjusted net income back below the threshold. Someone in the £60,000 to £80,000 band who contributes enough to reach £60,000 removes the charge completely and picks up higher-rate relief on the contribution at the same time. The contribution has to land by 5 April to count for that tax year.
Should I stop claiming Child Benefit if I earn over £80,000?
Not necessarily. Registering the claim and opting out of payments preserves the National Insurance credits that count towards the state pension for the parent at home, and gets the child a National Insurance number automatically. Stopping the claim entirely gives that up.
Can I use the PAYE route if I have already been filing Self Assessment?
Yes, provided the charge is the only reason you file. You need to de-register from Self Assessment first, because HMRC won't do it for you, and the service becomes available the day after. Tell HMRC by the 31 January following the tax year. Anyone with other income that requires a return stays in Self Assessment.
If you're in the £60,000 to £80,000 band and want a second pair of eyes before you file, get in touch. I'm happy to run through the adjusted net income calculation with you and check whether a pension contribution before the year end is worth making.