Britain has recorded the biggest-ever monthly surplus in public finances since the early 1990s, putting the government on a strong footing in the run-up to Brexit, now less than 40 days away.

In a rare piece of positive economic news for Philip Hammond as he prepares for his spring statement next month, income from taxes outstripped public spending by £14.9bn, the biggest January surplus since records began in 1993.

Although January is typically a surplus month for the exchequer because of seasonal trends in the payment of taxes, the Office for National Statistics said last month’s surplus was £5.5bn larger than a year ago.

Income and capital gains tax receipts increased by 14%, twice the average growth rate earlier in the year. Combined, the income from self-assessed income taxes and capital gains tax receipts was £21.4bn, the highest in January since comparable records began in 2000.

The data comes after several disappointing months for the chancellor, as borrowing came in worse than forecast. Government borrowing for the first 10 months of the financial year has, however, fallen almost by half, as tax receipts have been much stronger than expected.

The exchequer has borrowed about £21.2bn this year so far, £18.5bn lower than at the same point a year ago, and the lowest since the 10 months to January 2001.

The latest update means the government could be on track to reduce the deficit – the gap between spending and tax income – close to its target of £25.5bn set by the Office for Budget Responsibility, which is 39% less than in 2017-18.

However, Hammond has been told he needs to raise spending in order to meet Theresa May’s pledge to bring austerity to an end after almost a decade of cuts to benefits and public services under the Conservatives.

The chancellor has promised to hold about £15bn of spending firepower in reserve to safeguard the economy from a damaging no-deal Brexit scenario. Sluggish economic growth since the start of the year, as Brexit uncertainty bites and the global economy slows, could also drag on the public finances.

Changes to the way student loans are accounted for by the ONS will also undermine the public finances, when the alterations are made in September. The shake-up, to count loans as part-spending and part-financial asset, could create a black hole in the public finances worth as much as £12bn.

Martin Wheatcroft, an adviser on public finances to the Institute of Chartered Accountants in England and Wales, said: “Will the Chancellor take the politically tough decision to raise taxes to increase funding for public services, borrow more to provide an economic stimulus, or will austerity have to continue for even longer?”