GORDON BROWN was accused by the Liberal Democrats this weekend of carrying out a £3 billion stealth-tax raid on British pensions and funds.

The Lib Dems claim that changes to the rules governing empty-property rate relief will wipe some £3 billion from the value of commercial properties owned by British pension and life-insurance funds, which control £250 billion of commercial buildings.

Matthew Oakeshott, a Liberal Democrat Treasury spokesman and property-fund manager, calculates that the changes to empty-property rate relief will wipe £150m a year from the net rental income of property owned by pension funds. This will hit the market value of the buildings, which is calculated on the amount of net income they produce as investments.

Under the new system, office and shop landlords will have to pay rates on properties that have been empty for three months or more. Previously, they had to start paying only when properties had been empty for six months.

Industrial property owners will have to pay rates on properties that have been empty for six months or more. Before, they did not have to pay any rates on empty industrial buildings.

The Treasury argues that the changes will act as an incentive to re-let property more quickly.But Oakeshott insists the changes will hit even well-managed pension funds, which inevitably have empty units within shopping centres, office blocks and industrial estates.

Void periods are often necessary to allow landlords to refurbish buildings when a tenant leaves, and if a tenant goes bust it can take several months for the landlord to get the property back from the administrator or receiver and find a replacement.

Oakeshott said: “Six months is a reasonable time period to re-let an office block or shopping centre — three months is not.

“Reducing the time period for voids on offices and shops is a tax hitting well-managed pension-fund property.”

He added: “This shows that the Treasury has no idea how the property market works — especially after the fiascos over the abolition of stamp duty on commercial property in disadvantaged areas and the u-turn over putting residential property in self-invested pension plans.”