Return errors
VAT Return Error
How to correct an error on a submitted VAT return, current thresholds and the right notification method.
At a glance
- Small VAT errors can often be adjusted on your next return, without separate notification
- Larger errors generally need to be reported to HMRC directly using the formal correction process
- Using the wrong correction method can itself create a compliance issue
- A systemic VAT error needs fixing at the source, not just correcting past figures
- System or process errors need both a backward correction and a documented fix going forward
- HMRC may ask what's been done to prevent a systemic error recurring, which is relevant to any penalty
Errors on VAT returns are corrected differently depending on their size and age. Below a certain value threshold, many errors can simply be adjusted on the next VAT return rather than requiring separate notification to HMRC. Larger errors, or ones above the relevant threshold, generally need to be reported to HMRC directly using the appropriate error correction process rather than folded into a routine return.
Getting the correction method right matters, since using the wrong route can itself become a compliance issue. It's also worth checking whether an error is a one-off mistake or symptomatic of a systemic issue — such as a consistently wrong VAT rate being applied to a particular product line — since a systemic error usually needs correcting at the source, not just adjusting the numbers for one period.
Where an error correction is submitted formally, HMRC reviews the explanation and figures provided, and may ask follow-up questions if the calculation or the reason for the error isn't entirely clear. Keeping a clear internal record of how the error occurred, and what's been changed to prevent it recurring, is useful both for HMRC's review and for demonstrating that the business takes its VAT compliance seriously, which can be relevant to how any associated penalty is assessed.
Some errors arise from systems or processes rather than a single mistake — for example, a point-of-sale system misconfigured to apply the wrong VAT rate to a product category. In these cases, it's worth documenting both the correction of past returns and the fix applied going forward, since HMRC may ask what steps have been taken to prevent the same error recurring, particularly where a penalty for carelessness is being considered.
How to prepare
Taking a structured, evidence-led approach from the outset — rather than reacting to each request as it arrives — tends to produce a faster and less stressful outcome.
- 1
Establish exactly which return period and figure the error relates to
- 2
Calculate the total value of the error across all affected periods
- 3
Check whether the error falls above or below the relevant correction threshold
- 4
Identify the root cause to prevent the error recurring
- 5
Choose and use the correct notification method based on the error's size
- 6
Identify whether the error stems from a system or process issue, not just a one-off mistake
- 7
Document any fix applied to prevent the error recurring on future returns
What documentation to gather
- The VAT return containing the error and the correct figures
- Workings showing how the error arose and its total value
- Evidence of whether the error is a one-off or a recurring pattern
- Sales or purchase records affected by the error
- A note of which correction method was used and when
- A description of the root cause, especially for systemic or repeated errors
- Evidence of any fix applied to your systems or processes going forward
Common mistakes to avoid
These are the errors we see most often in practice — being aware of them in advance can help you avoid an entirely preventable setback.
Using the informal adjustment route for an error that's actually above the notification threshold
Correcting the current period without checking if the same error affected earlier returns
Not investigating the root cause of a recurring error
Assuming a VAT error is minor without properly calculating its total value
Delaying correction while continuing to make the same mistake on subsequent returns
Correcting past returns without fixing the underlying system or process causing the error
Not documenting the steps taken to prevent recurrence, which can affect how any penalty is assessed
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What happens next
Knowing the typical sequence of events helps you feel more in control and know roughly what to expect at each stage.
You calculate the value and cause of the error across all affected periods
You correct it using the appropriate route based on its size
HMRC reviews the correction and may ask clarifying questions
Any additional VAT due, plus interest, becomes payable
A pattern of errors may prompt a broader compliance check into related areas
Where a systemic cause is identified, HMRC may ask what's been done to prevent it recurring
Evidence of a prompt, thorough fix can influence how any penalty for the error is assessed
Frequently asked questions
The questions we're asked most often about this specific situation, answered in plain English.
Can I just correct a VAT error on my next return?
For errors below the relevant threshold, yes — but larger errors generally need to be notified to HMRC directly using the formal error correction process rather than adjusted informally.
Will correcting a VAT error trigger a penalty?
A genuine error corrected proactively is treated much more favourably than one HMRC identifies itself, and penalties for careless errors can sometimes be reduced or avoided through prompt disclosure.
What if the same VAT error has been repeated over several periods?
A recurring error usually needs correcting across all the affected periods, not just the most recent one, and identifying the root cause helps prevent it continuing.
What's the current threshold for adjusting a VAT error on a later return?
The threshold is set by HMRC and can change, so it's worth checking the current figure before deciding whether informal adjustment or formal notification is the correct route for your error.
Do I need to tell HMRC about an error I've already corrected?
If the error is below the relevant threshold and has been properly adjusted on a later return, separate notification usually isn't required, but formal notification is needed for larger errors.
Can a VAT error affect my other tax returns?
It's possible, particularly if the error relates to how income or expenses are recorded more generally, so it's worth checking whether it has any knock-on effect on your accounts or Corporation Tax position.
What if the same VAT error affects multiple products or services?
The total error across all affected items and periods needs to be calculated together, since the correction threshold is based on the cumulative value, not each individual instance.
Can I get a penalty reduced by fixing the root cause?
Demonstrating a prompt, thorough fix to prevent recurrence is generally viewed favourably and can be relevant to how any penalty for carelessness is calculated.
Do I need to tell my accountant about every VAT error?
Yes, even small errors are worth flagging, since your accountant can help assess whether the correct notification method has been used and whether any pattern needs addressing.
How long do I have to correct a VAT error?
Time limits apply, generally running from the end of the relevant VAT accounting period, so older errors should be reviewed for whether they're still within scope for correction.
Does a VAT error affect my flat rate scheme eligibility?
It could, particularly if the error relates to turnover calculations used to determine scheme eligibility, so it's worth checking this alongside the correction itself.
Can an error correction result in a VAT refund?
Yes, if the error means you've overpaid VAT, the correction process works the same way and should result in the overpaid amount being repaid or credited.
Read the full guide
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