Thousands of retirees face being £3,500 worse off in retirement from April, when extra payments to adult dependents come to an end.
The adult dependency increase is usually paid to a spouse or civil partner who is below state pension age and financially depends on someone claiming the basic state pension.
These extra payments closed to new applicants in 2010, but those who were already in receipt of them at that time could carry on claiming it.
From 6 April 2020, all these payments will stop and around 11,000 people are set to be affected in 2020/21, according to a freedom of information (FOI) request obtained by Royal London.
The FOI request estimated that the total amount lost will be around £33 million, with each individual affected losing £70 a week.
Steve Webb, director of policy at Royal London, said:
"Under the old state pension system, people claiming a retirement pension could get a significant extra amount for a spouse who was financially dependent on them.
"Although that addition was abolished for new claims in 2010, many people already in the system have continued to benefit.
"It will come as a shock to thousands of people to see their state pension cut by up to £70 per week.
"Losing over £3,500 per year overnight will make a material difference to the standard of living of those who are affected."
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