UK government borrowing exceeded official forecasts in July despite record self-assessment income tax receipts, underlining the fiscal pressures facing the government ahead of the Autumn Budget.

Public sector net borrowing was £1.8bn in July, £700mn higher than a year earlier and £2.3bn above the Office for Budget Responsibility's forecast, according to the Office for National Statistics.

July typically provides a boost to the public finances because of self-assessment tax payments. Receipts from self-assessed income tax reached £17.1bn, £1.7bn higher than a year earlier and the highest recorded for any July since monthly records began in 1999. However, they were £400mn below the OBR's forecast.

Overall central government current receipts increased 4.6 per cent year on year to £104.3bn. Total tax receipts rose to £81.4bn, including increases in VAT, corporation tax and income-related taxes.

Higher revenues were nevertheless outweighed by increased government spending. Central government borrowing reached £6.4bn during the month, £1.1bn more than in July last year.

For the first four months of the financial year, public sector borrowing totalled £56.7bn. That was £6bn lower than during the same period last year but remained £2.3bn above the OBR forecast.

The government's debt burden also remains elevated. Public sector net debt stood at £2.98tn at the end of July, equivalent to 94.1 per cent of gross domestic product, although the debt-to-GDP ratio was 0.8 percentage points lower than a year earlier.

The OBR's March forecast projected borrowing would decline over the medium term, while warning that the outlook remained particularly uncertain because relatively small changes in government receipts or expenditure can produce large changes in the deficit.

Commenting on the latest figures, Dennis Tartakov, senior economist at KPMG, said stronger self-assessment receipts had "not been enough to put public sector borrowing back on track this fiscal year".

"Looking ahead to the Autumn Budget, while the Chancellor may be tempted to use leeway in the fiscal rules to boost spending, the market's appetite for more debt is limited," they added, pointing to the UK's elevated government borrowing costs.