An estimated 16 million people – or 29% of UK adults – experienced post delays with Royal Mail over Christmas, Citizens Advice has said.

The figure, which applies to letters and cards but not parcels, is a 50% increase on December 2024, up from 10.7 million people, the charity found.

Some 5.7 million people missed vital letters about health appointments, fines, benefit decisions and legal documents, it warned.

Aside from 2022, when Royal Mail took strike action, the charity’s annual research found the number of people experiencing these issues over the festive period was the highest in five years.

Citizens Advice, the statutory watchdog for post, said not enough was being done to prioritise consumers who had “no choice but to put up with delivery delays and service cuts, despite increasing stamp prices”.

Among those who send or receive post with Royal Mail, 36% said they sent fewer Christmas cards in 2025 because stamps were too expensive.

Another 34% reported not getting post for between one and three weeks at a time, then receiving a bunch of five or more letters in one go.

Almost a quarter of those who experienced post delays (22%) said they were left feeling anxious or distressed about benefits, bills, losing money and missing other financial information.

The cost of a 1st class stamp, now £1,70, has more than doubled since 2020 despite Royal Mail failing to meet a 1st class annual delivery target since 2017 or a 2nd class target since 2020.

In July last year, regulator Ofcom announced cuts to Royal Mail’s 2nd class delivery days alongside lower delivery targets as part of the review of the Universal Service Obligation (USO).

The company now only has to deliver 2nd class post every other weekday, instead of six days a week, with these changes set to be rolled out nationwide this year.

Anne Pardoe, head of policy at Citizens Advice, said: “We’re afraid there’s no light at the end of the tunnel for consumers struggling with Royal Mail’s persistent delivery failures. When people have no other postal provider to choose from, the sheer volume of delays is simply unacceptable.

“The company’s dreadful festive slump is about much more than late Christmas cards. People are left distressed after missing health appointments, fines and benefit decisions.

“This is a worrying trend, and with cuts to delivery days looming, Ofcom must start cracking down even harder on missed targets before things go from bad to worse. Any future stamp price increases should be conditional on Royal Mail meeting these targets.”

A Royal Mail spokesman said: “Independent data shows that more than 99% of items posted by the last recommended dates arrived in time for Christmas.

“This was during our busiest time of year, when volumes more than double, and we’re grateful to our teams across the country who worked incredibly hard to deliver for our customers.”

An Ofcom spokesman said: “In recent years, we’ve fined Royal Mail £37 million for its poor letter delivery performance, and we’ll continue to hold the company to account.

“Last year, we modernised the obligations imposed on Royal Mail, to reflect what people need, put the service on a more sustainable footing, and enable the company to invest more in improving its delivery performance.

“Royal Mail must now play its part by implementing this effectively and improving its reliability.”

Yonder surveyed 2,095 UK adults between January 5-6.