Chancellor Philip Hammond has been given a boost after official figures showed Government borrowing declined in May, helped by higher tax receipts.
Public sector net borrowing was £5 billion year on year in May, down from to £7 billion, the lowest since 2005, the Office for National Statistics (ONS) said.
The figure was lower than economists' forecasts of £6.3 billion and was helped by an increase in receipts, which grew 3%.
Borrowing in the current financial year to date was £11.8 billion, a total of £4.1 billion less than in the same period in 2017.
The figure is the lowest year-to-date net borrowing since 2007.
The ONS also revised down borrowing for the year to the end of March to £39.5 billion from £40.5 billion, the lowest figure in 11 years.
Samuel Tombs, chief UK economist at Pantheon Macroeconomics, said that while the headline borrowing figures "look fantastic", the rate of improvement will not be sustained.
"Central government tax receipts rose by just 3% year over year in April, below the 3.6% full-year increase predicted by the OBR. Lower-than-anticipated borrowing is not a sign of a healthy economy," he said.
Public sector net debt totalled £1.78 trillion at the end of May, equivalent to 85% of gross domestic product.
Howard Archer, chief economic adviser to the EY Item Club, added: "The lower May deficit boosts hopes that the economy has gained significant momentum in the second quarter after a poor first-quarter performance which was seemingly only partly due to the severe weather in late February and March."