How Long Does HMRC Take to Fix a Wrong Tax Code?
HMRC promises quick tax code fixes, but the reality is far slower. Here is exactly how long it takes, why it drags, and how to speed it up.
Every month your tax code stays wrong, HMRC quietly takes money that is not theirs. So how long does HMRC take to fix a tax code, and why does it sometimes feel like waiting for a bus that may never arrive?
- HMRC officially aims to update a tax code within 2 weeks of receiving correct information, but real-world waits of 6 to 12 weeks are common during busy periods.
- Your employer or pension provider cannot change your tax code themselves; they must wait for HMRC to issue a new PAYE coding notice (P9 or P6).
- Every week on the wrong code at a basic-rate salary of £35,000 can cost you £15 to £30 in overpaid tax, depending on how far off the code is.
- Contacting HMRC by phone is faster than writing; online requests via your Personal Tax Account typically trigger updates within 10 working days.
- You can check your current tax code for free at /check-my-tax-code before you contact HMRC, so you know exactly what you are asking them to change.
The Official Answer versus the Actual Answer
HMRC's own guidance states that when you report a change of circumstances, your tax code should be updated within two weeks. That figure appears on GOV.UK and sounds entirely reasonable. The problem is that it applies to a smooth, frictionless process where HMRC already holds accurate information and your request is straightforward.
For the majority of people asking how long HMRC takes to fix a tax code, the context is messier: a company car benefit that was removed six months ago, a second job that finished but is still depressing your main code, a marriage allowance transfer that never made it through, or a pension income that bumped you into a higher-rate bracket nobody told you about. In those cases, two weeks is optimistic.
Based on reports to the HMRC customer service forums and the Adjudicator's Office, which handles complaints about HMRC service, real-world waits regularly stretch to six weeks. During January, February, and the period immediately after the April tax year-end (when HMRC processes millions of P60s, annual coding notices, and employer submissions simultaneously), delays of eight to twelve weeks have been documented. The Adjudicator's 2022/23 annual report noted that handling times for correspondence had extended significantly, with some written enquiries taking over 12 weeks to receive a substantive reply.
- PAYE Coding Notice
- A document (form P9 for employers, P6 for in-year changes) that HMRC issues to your employer or pension provider instructing them to operate a new tax code. Your employer cannot legally change your code without one.
Why the Wait Is Not Your Employer's Fault
A persistent frustration for employees is ringing their payroll department, being told the fix is on its way, and then watching the same wrong code appear on next month's payslip. The temptation is to blame HR. In most cases, that blame is misplaced.
Under the PAYE system, your employer is legally obliged to operate the tax code that HMRC has instructed them to use. They cannot simply type in a new number because you have asked nicely. They must receive a formal P6 notice from HMRC first. If payroll runs on the 20th of the month and your P6 arrives on the 21st, you will wait another full month regardless of when HMRC actually updated their systems.
This is the silent delay that nobody mentions: even when HMRC processes your request in two weeks, if that update lands after your payroll cut-off date, the financial correction does not reach your pay packet for another four to six weeks. The total elapsed time from your original call to money back in your account can therefore be six weeks for a textbook case, and considerably longer when anything goes wrong.
What Actually Triggers the Update
Understanding the mechanism helps you push it along. HMRC adjusts tax codes in response to three main inputs.
Real Time Information (RTI) from your employer. Since 2013, employers have submitted payroll data to HMRC every time they pay you. If your salary changes, a benefit is added, or you leave a job, this information flows to HMRC automatically. In theory, HMRC's systems should spot the discrepancy and issue a revised code. In practice, the automated reconciliation takes time and does not always catch edge cases, particularly if you have multiple income sources or if a previous employer's records are outstanding.
Your own report via Personal Tax Account. Logging into your Personal Tax Account at gov.uk/personal-tax-account and updating your circumstances directly is generally the fastest route. HMRC's internal guidance treats these as higher-priority than written letters. Updates made this way typically generate a new coding notice within 10 working days, though that is still two calendar weeks before the notice even reaches your employer.
A phone call to HMRC. The income tax helpline (0300 200 3300) can process straightforward changes during the call. An advisor with the right access can flag an update immediately, which then takes the usual processing time to filter through to your employer. The downside is the wait to get through: HMRC's own data showed average call wait times exceeding 20 minutes in 2023/24, and the National Audit Office has repeatedly criticised the accessibility of HMRC phone lines.
The Cost of Every Week on the Wrong Code
Abstract discussions about tax codes become very concrete when you run the numbers. Take someone earning £42,000 a year, paid monthly. They should be on the standard 1257L code, giving them a monthly tax-free allowance of roughly £1,048. But they are sitting on a BR code (basic rate on everything) because a previous employer never told HMRC the job had ended.
On BR, every pound of their £3,500 monthly salary is taxed at 20%. On 1257L, the first £1,048 is tax-free. The difference in monthly take-home is approximately £210. Every week that code stays wrong costs this person roughly £52. Over a 12-week HMRC delay, that is £624 they have effectively lent to HMRC interest-free.
They will eventually get it back; HMRC will either adjust the code for the remainder of the year to claw back the overpayment through bigger paycheques, or they will issue a P800 refund letter after the tax year ends. But "eventually" is doing a lot of work in that sentence, and not everyone realises a refund is owed. As we explored in Claim Back Overpaid Tax: Why HMRC Won't Chase You, HMRC is under no legal obligation to proactively hunt you down and return your money.
Before you even dial HMRC, it is worth confirming exactly what code you are on and what it should be. Check your tax code for free at /check-my-tax-code so you walk into the conversation knowing precisely what you are asking them to change.
How to Accelerate the Process
You cannot force HMRC to work faster, but you can remove every obstacle that might slow them down.
Use your Personal Tax Account first
Log in, navigate to "Check your Income Tax" and then "Tell us about a change." Online submissions create a digital audit trail and avoid the transcription errors that occasionally occur on phone calls. HMRC's own processing data suggests online updates are actioned slightly faster than correspondence.
Have your information ready before you call
If you do call, HMRC advisors need your National Insurance number, your employer's PAYE reference (on your payslip or P60), the incorrect code you are currently on, and the reason it is wrong. The faster you can give them clean information, the less likely the call is to end with "we'll look into it" and a note on your file that nobody reads for three weeks.
Follow up if nothing changes in 15 working days
HMRC does not proactively update you on progress. If your payslip still shows the wrong code after 15 working days, call again and reference your original contact. Escalating to a formal complaint, while tedious, does tend to accelerate resolution. HMRC's complaints team has a 15-working-day target to resolve simple cases.
Write to HMRC for complex cases
If your situation involves multiple income sources, a company car, underpaid tax being collected through your code, or anything that cannot be resolved in a 10-minute call, a written letter to HMRC PAYE, PO Box 1970, Liverpool, L75 1WX creates a formal record. Include copies of any P45s, P11D benefit statements, or bank statements relevant to your case. Complex written cases take longer upfront but are less likely to be resolved incorrectly and then need fixing again.
For situations where HMRC has embedded underpaid tax from previous years into your code (which shows as a K code or a reduced allowance number), the process is more involved. HMRC Wrong Tax Code Contact: What They Can Actually Fix covers the specific scenarios where HMRC can and cannot adjust historical underpayments through your code.
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The Hidden Delay Nobody Talks About: The P6 Lag
Even when HMRC processes your update perfectly and on time, there is a structural delay built into the PAYE system that catches people out. When HMRC issues a P6 notice to your employer, that notice enters your employer's payroll software queue. Small employers running their own payroll may not log in for days. Large employers processing thousands of employees in a weekly batch may not apply the change until their next scheduled payroll run.
HMRC updated its employer guidance in 2022 to state that employers should apply a new coding notice by the next payroll run after they receive it, not the one after that. But compliance is inconsistent, particularly among smaller businesses that use a payroll bureau or accountant who only accesses the system once a month.
If you suspect your employer has received a P6 but has not applied it, ask HR or payroll directly. Show them the date your Personal Tax Account was updated. Most employers will apply the change immediately once a staff member flags it; very few are deliberately slow.
When the Timeline Is Genuinely Someone Else's Fault
Sometimes the delay is not HMRC processing speed but incorrect information feeding the system. Your previous employer may not have submitted a final RTI return. A benefit-in-kind declared on a P11D might be incorrect. A pension provider may be reporting a different income figure to HMRC than the one appearing in your account.
In these cases, HMRC's systems are working exactly as designed; they are just working with bad data. Fixing the code requires correcting the underlying data first, which means contacting the relevant third party (former employer, pension provider, letting agent) and asking them to resubmit accurate figures to HMRC. This can add weeks to the process and is why some tax code errors persist stubbornly despite multiple calls.
If you have multiple sources of income and your code looks unusual, the Tax Code on Your Payslip: What Each Part Actually Means guide will help you decode exactly what HMRC has built into your number before you start making calls. Knowing whether your reduced allowance reflects a company car, a previous underpayment, or simply an administrative error changes which conversation you need to have.
Start the Clock Today
Remember that question at the top: how long does HMRC take to fix a tax code? The honest answer is two weeks if everything is straightforward, six to twelve weeks if it is not, and indefinitely if nobody pushes. The single most useful thing you can do right now is confirm whether your code is actually wrong before the clock starts.
Check your tax code for free at /check-my-tax-code, identify what it should be versus what HMRC is currently operating, and then contact HMRC the same day. Every week you wait before starting that process is a week added to the timeline and, quite possibly, another £15 to £50 sitting in HMRC's pocket that belongs in yours.
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