Experts have warned that Rachel Reeves’ so-called retirement tax disproportionately penalises the oldest pensioners in society. According to data analysis, nearly half (46%) of retirees aged between 85 and 89 have state pensions that breach the £12,570 tax-free threshold, compared to just 22% of retirees under 85, according to the Telegraph’s analysis of Department of Work and Pensions data. That means that those born between the years of 1935 and 1940 could likely be affected.

The state pension triple lock has pushed many into higher tax brackets, which former prime minister Rishi Sunak dubbed the “retirement tax”, and experts warn it could penalise society’s most vulnerable. Caroline Abrahams, director of charity Age UK, has called on the government to increase the personal allowance so that pensions don’t have a “disproportionately adverse impact” on the oldest people.

She added: “People in this age group are much more likely to be in ill-health and also to find their savings have dwindled over the years, compared to others who have only recently retired.”

Older pensioners in particular are likely to pay larger bills because many fall into the pre-2016 pension system, which allowed retirees to boost their pensions.

It was based on a two-part pension, with flat-rate payments and an additional earnings payment, known as Serps, which could significantly add to income.

Former pensions minister Baroness Altmann warned that more retirees “may be dragged into the tax net” if the state pension increases while the tax threshold stays frozen.

Altmann added: “The most elderly may be unable to cope with tax returns leaving them vulnerable to fines or penalties for failing to pay small amounts of tax.”

Steve Webb, a former pensions minister, warned that while the majority are under the tax threshold, “most new state pensioners” will be taxpayers regardless of any other income in the next two years when the standard new pension exceeds the threshold.

He added: “People whose pension comes mainly from the state rather than a workplace pension can easily find their total state pension takes them into the income tax bracket.”

The triple lock is expected to push anyone receiving the new state pension past the £12,570 personal allowance as early as April 2027.

An HM Treasury spokesman said: “We are committed to help our pensioners live their lives with dignity and respect, which is why we have frozen fuel duty and increased the state pension to leave pensioner couples up to £88 better off a month. Our commitment to the triple lock means millions will see their pension rise by up to £1,900 this parliament.”