It’s a common misconception to think, “I’m on PAYE, so my employer sorts out my tax and it’s always right.” In fact, over one in three tax reviews we carry out result in a refund for our customers. It’s clear that every taxpayer should take the time to check their tax code.

Your employer deducts tax from your wages using the tax code issued by HMRC. They’re legally required to use this code exactly as provided—they don’t check whether it’s correct.

If your tax code is wrong and you don’t spot it or tell HMRC, the wrong code will keep being used. HMRC also doesn’t automatically check that your tax code is correct.

The result? If you’ve been issued an incorrect tax code, your employer will deduct the wrong amount of tax from your pay and more often than not, it will be too much!

You should check your tax code at least once a year,but in practice, there are a few key moments when you really should double-check it:

At the start of a new tax year (UK tax year starts 6 April)

• HMRC often issues new codes then.

Whenever you change jobs

• Employers get your code from HMRC, but errors happen.

If your income changes significantly

• Pay rises, bonuses, going part-time, second job.

If you start/stop receiving benefits or pensions

• These can alter your allowances.

After claiming expenses or reliefs

• These should be reflected in your code, but aren’t always.

If HMRC sends you a new tax code notice

• Always check it carefully.

There are a few key reasons you might have overpaid tax.

First, HMRC may have made an error in your tax code. Even a small mistake can mean you’re taxed more than you should be.

Second, you might not have known about certain tax allowances you were (or at the time, were) eligible for. Some allowances have been phased out, but if you didn’t know to claim them when they applied, HMRC wouldn’t have included them in your tax code. As a result, you could have paid more tax than necessary without even realising it.

If you don’t know there’s an error or missing allowance, you can’t tell HMRC about it—and HMRC will simply confirm that your tax code is correct based on the information they have from you.

The good news? It’s not too late to claim a refund. HMRC allows you to go back up to four years to correct errors or claim any allowances you missed.

However, there’s a catch. Unless you know exactly what to look for, it can be hard to spot mistakes or identify allowances you were entitled to. If you don’t claim what you’re owed in time, HMRC will simply keep your money. There’s a strict deadline for these claims—so acting quickly is essential to make sure what’s rightfully yours ends up back in your pocket, not HMRC’s.

We’re asked this nearly every day! Your employer has to use the tax code they’re given by HMRC. If the code’s wrong, your employer can’t do anything about it. It’s up to you to check the code and make sure HMRC has given them the right one. If it’s wrong, it’s your responsibility to get it corrected as soon as possible.

We offer a flexible range of services and fee options designed to suit your needs and budget.

Every service tier includes the same meticulous review process, ensuring every case receives equal care and attention.

For those seeking more comprehensive support, we also provide expert case management, claim handling, and repayment checks. These enhanced services are ideal if you’d prefer to leave the entire process to us.

Even with our standard review, you’ll receive clear, practical guidance on managing error correction and overpayment claims yourself. And if you need extra help at any stage, we’re always ready to step back in and support you.

See our FEES PAGE for more detailed information

Absolutely, if you’ve received more than one pension, or paid tax on your pension in the last four years, it’s well worth reviewing your tax. Click the green “Check Now” button at the top right of your screen, and let us check it for you.

Free Instant Check

Our free instant check tool asks a few simple questions and takes just a couple of minutes to complete. It will tell you immediately whether it’s worth proceeding with a full review. If we believe you could benefit from one, we’ll invite you to take the next step.

Standard Review

The time required for a full review depends on the complexity of your case and how quickly you can respond to any follow-up questions. Most of the information we need can be gathered through our intelligent online process. This system draws on years of experience and data to ask tailored questions relevant to your circumstances.

Completing this stage typically takes between 5 and 15 minutes. You can save your progress at any time and return later via your personal To-Do list.

Once all the necessary information has been provided, we’ll conduct your review and share our findings with you within 7 days.

Fully Managed Service

If you choose one of our fully managed services (Review and Correct or Commission Service), we will handle submitting any requests for error corrections and refunds to HMRC on your behalf, typically within 7 days of completing your review.

Important: In the rare event that we identify an underpayment of tax (meaning you owe HMRC), we do not automatically submit this information. Instead, we will always discuss the matter with you first and follow your instructions.

Once your case is with HMRC, their response time is generally 6–8 weeks, though this can vary depending on their workload. You can check the latest HMRC turnaround times here:

Check when you can expect a reply from HMRC

Refund Payments

If you’re due a refund through one of our fully managed services, we will:

• Verify the amount received from HMRC
• Issue payment to you within 2 working days of receiving it

If we believe HMRC hasn’t sent the full amount, we will continue to pursue the balance on your behalf and forward any additional payments within 2 working days of receipt.

YES! If you’re determined, well-informed, and have plenty of patience, you can attempt to claim a tax refund yourself through HMRC. But to do so successfully, you’ll need to know exactly which aspects of your tax records to review for each of the past four tax years. You’ll also need to identify the specific allowances you were eligible to claim, spot any errors made by HMRC or your employer, and most importantly, know precisely what questions to ask HMRC.

It also assumes you’re familiar enough with Pay As You Earn (PAYE) rules to recognise when HMRC’s answers are actually correct, which unfortunately isn’t always guaranteed. According to a survey by the Low Income Tax Reform Group, HMRC’s call centres gave incorrect answers in up to 80% of complex cases.

If you do secure a refund yourself, you’ll need to be confident the amount is correct. If HMRC overpays you, they’ll certainly want the excess back in the future, even if it’s already spent. But the greater risk is that they underpay you, leaving you with less than you were truly owed. And let’s be clear: if you didn’t ask the right questions or present the right information, that shortfall is usually on you, not HMRC.

Another important consideration rarely mentioned by “DIY” tax guides is that when you ask HMRC to review your records, they may discover you owe them money. Sometimes they’re right but we regularly see cases where the amount they demand is significantly inflated. In fact, over half of the underpayment cases we review turn out to be wrong. Without expert help, you may have little choice but to pay the amount they demand, which they can simply deduct from your future wages.

Remember we will always discuss an underpayment case with you before HMRC, Let us find it rather than them!

By choosing our service, you’ll avoid these risks. We know exactly what to look for, having helped over 3 million taxpayers since 1993. We only contact HMRC if we believe you’re genuinely owed a refund so you get peace of mind that your claim is being handled correctly and professionally.

If you’re unable to provide all the information we’ve requested, please share as much as you can. We can still assess your case and may be able to find the remaining details from other sources.

If you need help locating any information, feel free to ask us. You’ll also find plenty of guidance on our website and in our online process, just click on the ⓘ (information) symbols for more support.

It’s rare, but if we think that you’ve underpaid tax, we’ll let you know directly—we don’t notify HMRC.

We always recommend resolving any underpayment promptly. If HMRC finds it first, they may add interest and penalties.

To help you, we can provide a detailed fact sheet on how to handle underpayments.

And if you’re on one of our fully managed services, you’re covered by our Underpayment Guarantee: if you receive an unexpected tax bill that results directly from our error, we’ll cover the tax owed. (T&C’s available here).