Heathrow has accused Rachel Reeves of an “own goal” on tax, warning that a planned £500m increase in the airport’s business rates bill will undermine pro-growth expansion plans.

The airport said proposals for a fivefold rise in its business rates bill from the current £121m would be “unacceptable” to any company.

It called on the Chancellor to reconsider the increase, warning that implementing it in full would make a mockery of her strategy of using airport expansion to kickstart the economy.

A spokesman said: “It seems like an own goal. We don’t see how the Chancellor can allow it, especially when she has made Heathrow central to the Government’s growth strategy.

“We’re not some sort of bank with unlimited money. We already have the highest rates in the country so we’re more than paying our share.

“It’s just a ridiculous increase and coming with the other taxation that we’re seeing it feels like an attack on aviation.”

The airport, which is awaiting the go ahead from Labour for construction of a third runway as part of a £49bn expansion, said that Ms Reeves should “step in at the Budget to address these punishing increases and pursue a longer-term rethink”.

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At the very least, Heathrow wants the Chancellor to phase in the rate increase by introducing interim relief.

Heathrow and other UK airports are expected to see their rates payments soar from next April following an assessment by the Treasury’s Valuation Office Agency (VOA).

The revaluation will be based on profits generated in 2024. The previous assessment was based on 2021 profitability, when passenger numbers and ticket sales were at an all-time low due to Covid.

Compounding the issue, airports also face a new 10 pence in the pound supplement intended to fund lower rates for struggling pubs and restaurants. That would equate to a further £21m expense for Heathrow even at current rateable values.

Heathrow, Gatwick, Stansted and Manchester airports are all among the top 20 UK business rate-payers, but following the revaluation they are expected to occupy the top four positions.

Heathrow’s bill could be 20 times higher than the first non-airport on the list, which last year was the Sellafield nuclear reprocessing plant in Cumbria, with a payment of around £28m.

The rates hit to airports has been magnified by the adoption of an income-based calculation model, which replaced one based on construction costs for a similar hypothetical building.

The VOA is understood to be in dialogue with companies that have been informed of their new rateable values and are able to question them on the basis of any factual errors.

A spokesman for the agency said a draft list of the new values will be made public before the end of the year, potentially within a few days of the Budget.

Tax experts Ryan said transitional relief to phase in tax increases represents “an important shock absorber for those ratepayers facing very large increases in liabilities”.

It said it expects a relief scheme for the 2026 revaluation to be announced at the Budget. Under the previous three-year cycle, bill increases were capped at 30pc in the first year.

The Treasury was contacted for comment.

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