George Osborne's borrowing targets will be hard to meet

The slowing economy will mean fewer tax receipts but more speculation on whether spending cuts or tax rises are needed to reach a 2020 budget surplus

Earlier this week the Treasury made some confident projections about what the economy would look like in 2030 in the event of a vote to leave the EU in June's referendum. The hazards of forecasting even one month ahead have now been illustrated.

At the time of the budget, the number crunchers at the Office for Budget Responsibility (OBR) said they expected the UK to have to borrow 72.2bn to balance the books in 2015-16. The actual deficit turned out to be 74bn.

Related: UK misses borrowing target by 1.8bn