The next government will be forced to hit voters with post-election tax rises and delay net zero investment unless it is prepared to rip up Treasury rules for managing the state finances, a leading thinktank has said. The National Institute for Economic and Social Research (Niesr) called for a radical overhaul of the self-imposed constraints imposed on government borrowing and debt as it warned that persistently weak growth and lower inflation would make hitting the rules more difficult. In its quarterly health check, the thinktank said the economy had emerged from recession but the “not-fit-for-purpose” fiscal rules meant there was no scope for Jeremy Hunt to offer fresh tax cuts before polling day. After the general election, Niesr said a future chancellor would be faced with a choice: raise taxes to maintain the existing provision of public services or rewrite the rules so that they served the UK’s medium- and long-term needs and objectives – including raising the growth rate, levelling up the regions and greening the economy. Official growth figures are due out on Friday and Niesr said it expected output to have risen by 0.4% in the first three months of 2024. For 2024 as a whole, it...