Is Business Loan Interest Tax Deductible for a UK Limited Company?

The general rule: interest is deductible

When a UK limited company or LLP borrows money for business purposes, the interest it pays is treated as a financing cost under HMRC's Loan Relationships rules (Corporation Tax Act 2009, Part 5). Provided the loan is used wholly and exclusively for trading or investment purposes, the interest is deducted from the company's profits before corporation tax is calculated.

In practical terms, if your company pays £10,000 in loan interest during an accounting period, that £10,000 reduces the profits on which corporation tax is charged. At the 25% main rate, that represents a £2,500 reduction in your tax bill. Confirm the precise treatment with your accountant, as the computation depends on the full picture of your company's income and costs.

Conditions HMRC expects to be met

Deductibility is not automatic. HMRC will look at whether the borrowing has a genuine commercial purpose and whether the interest charge is at arm's length. The key conditions are:

• The loan must be used for the company's trade, investment, or property business — not for personal benefit of shareholders or directors.
• The interest rate must be commercially reasonable; artificially high rates on related-party loans can be challenged.
• If the loan is from a connected party (e.g. a director or parent company), transfer pricing and thin capitalisation rules may apply and can restrict the deduction.

If a loan funds a mix of business and personal expenditure, only the business proportion of the interest is deductible. Document the purpose clearly at the outset.

Timing: when is the deduction taken?

Under the Loan Relationships rules, interest is generally recognised on an accruals basis, matching the period to which it economically relates rather than the date of cash payment. This means your accounts and tax return should reflect interest accrued during the accounting period, even if the payment falls slightly outside it.

Your accountant will ensure the loan is booked correctly in the statutory accounts, which forms the starting point for the tax computation. Errors in accounting presentation can create unnecessary HMRC enquiries.

Situations where deductibility can be restricted

Several anti-avoidance regimes can limit or deny interest deductions:

• Hybrid mismatch rules — where instruments produce a deduction in the UK but no corresponding income recognition elsewhere.
• Corporate Interest Restriction (CIR) — applies to groups with net UK interest expense exceeding £2 million; excess interest may be disallowed.
• Unallowable purpose rule — if a main purpose of the arrangement is to secure a tax advantage, HMRC can deny the deduction.

For the majority of straightforward SME borrowings these rules will not be triggered, but they are worth being aware of if your company is part of a larger group or the financing structure is complex. Take qualified advice before entering unusual arrangements.