Self Assessment overpayments: how refunds and offsets work


Few things feel as satisfying as discovering you have paid too much tax. Few things are as confusing as working out what happens next. If your Self Assessment account shows a credit balance, HMRC will either repay it to you or offset it against something else you owe, and which one happens is not always your choice. Here is how the system works and where people trip up.

Where overpayments come from

Overpayments are more common than most people expect. The biggest source is payments on account. If your bill for last year was, say, 8,000 pounds, HMRC asked you to pay 4,000 pounds in January and 4,000 pounds in July as advance payments toward this year's bill. If this year's actual bill turns out to be lower, perhaps because your income dropped, the difference sits in your account as a credit.

Other common causes: CIS deductions taken by contractors at 20 or 30 per cent when your final liability is lower; income taxed at source through PAYE on a second job alongside your Self Assessment income; or simply a payment entered twice or for the wrong amount. Credits can also appear after an amended return reduces your original bill, or after HMRC corrects an error on their side.

Repayment or offset: how HMRC decides

When a credit lands on your account, HMRC applies a simple hierarchy. Debts first, you second. Before any repayment reaches you, the credit is automatically offset against any tax you currently owe across your HMRC accounts: outstanding payments on account, late filing penalties, a balancing payment from a previous year, or even debts under a different head of duty like PAYE or VAT.

Only the amount left over after offsets is available for repayment. This surprises people who assume the full overpaid figure is theirs to claim. If you owe 2,000 pounds and are in credit by 5,000 pounds, expect 3,000 pounds as a repayment, and 2,000 pounds quietly absorbed by the debt. That is usually good news, since it stops interest and penalties building on the debt.

You can ask for the credit to be offset against a specific liability rather than repaid, and in some cases that is the smarter move. If your next payment on account is due in a few weeks, leaving the credit where it is saves a payment trip and avoids the risk of the repayment arriving after a new penalty has already started accruing.

How to request a repayment

If a refundable credit remains after offsets, you claim it through your online Self Assessment account. Log in, check your statement, and request the repayment to a nominated UK bank account. HMRC usually processes straightforward repayments within a few weeks, though the first time you claim, or if the amount is large relative to your history, additional checks can stretch the timescale.

A few practical points make the process smoother. Check that your bank details are up to date before you claim, because a repayment to a closed account means starting over. Wait until your tax return for the year has been processed; claiming against an estimated credit before the return is finalised can cause the request to bounce or to be partially reversed. And keep an eye on your statements afterwards, because HMRC sometimes splits a credit, offsetting part and repaying the rest, without explaining the split clearly.

The common pitfalls

The first pitfall is claiming a repayment you are about to owe back. If you request a refund of your July payment on account and then your balancing payment lands in January, you will simply be paying the same money back again. Check your full year's position, not just today's balance, before asking for money back.

The second is the timing of payments on account. HMRC will not repay a credit that it intends to apply to your next payment on account automatically. If the repayment request keeps stalling, this is often the reason, and the fix is to leave the money alone.

The third is interest. HMRC pays repayment interest on overpayments from the later of the payment date or the relevant deadline, currently at rates set by reference to the Bank of England base rate. It is taxable, so it goes on your next return. Small, but not nothing, and worth declaring properly.

The fourth, and the one that catches busy people, is forgetting the credit exists at all. An unclaimed credit can sit on a Self Assessment account for years. Log in and check your statement every year after your return is filed. It takes two minutes and sometimes turns up a welcome surprise.

If your Self Assessment position is getting complicated, payments on account, CIS credits, PAYE overlap, this is exactly the territory where tax compliance services pay for themselves. And if reconciling all of it is swallowing your time, Finex Outsourcing handles the returns, the statements and the HMRC correspondence so nothing slips through the cracks.

By John Thomas, Senior Accountant


 

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