Wandsworth households would see a dramatic uplift in local bills if the borough adopts a proposed 94% council tax rise, a change the Conservative leadership links to an £84m-a-year reduction in central grants and says it will legally contest.

The council’s plan would add £958 to the average bill, split with half of that set by the borough and half by the mayor of London. That calculation would shift Band D charges from just above £1,000 toward levels now common in many London boroughs where bills exceed £2,000.

The authority attributes the move to the government’s Fair Funding Review 2.0, a redistribution of local government grants that transfers money between councils. The reform temporarily permits six councils, including Wandsworth, to exceed the usual 5% council tax cap for two years after they chose to reduce their share of central funding.

Kemi Badenoch, the Conservative Party leader, described the proposed increase as "outrageous" and said, "we have actually instructed lawyers, as the Conservative Party, to see if we can challenge the government on this decision." She told BBC Newsnight she feared a near 100% rise would alarm families on fixed budgets, and she declined to propose an alternative rate while questioning why Wandsworth faced a 40% funding reduction when others had not.

Wandsworth’s Tory deputy leader said the rise will be hard for residents and pledged to continue to challenge the government "by every possible means." Labour councillor Simon Hogg also called the rise "outrageous", blaming recent council changes for the need to propose the increase.

A government spokesperson said local authorities set council tax levels and should "put taxpayers first." The spokesperson added, "We’re fixing an outdated funding system so funding goes where need is greatest, while protecting councils through the transition and ensuring no area faces a cliff edge."

Alongside Wandsworth, Kensington & Chelsea, Westminster, Hammersmith & Fulham and the City of London, plus Windsor and Maidenhead in Berkshire, have been granted the same temporary flexibility. Kensington & Chelsea, Westminster and Hammersmith & Fulham are reported to be considering joining Wandsworth in using the Sustainable Communities Act to challenge the cuts.

A final decision on Wandsworth’s budget is expected early next year. The combination of possible legal action and a binding local vote will determine whether the proposed increases take effect and how the borough manages the funding gap created by the redistribution.