TUC's annual PensionsWatch survey, which examines the pension arrangements of 294 directors across FTSE 100 companies, found the average accrued pension was £259,947 a year, and 25 times the average employee occupational pension of £10,452 a year.
Frank Chapman, the former head of oil and gas company BG group, was revealed as the richest pensioner in the FTSE 100 with a pot worth more than £22 millionwhen he stepped down earlier this year.
The study showed more directors are moving away from having defined benefit (DB) schemes. Cash payments in lieu of pensions have also increased sharply.
Over the past year, average annual employer contributions to directors' DC pensions increased by £15,872 to £160,380, though several directors receive company contributions of more than half a million pounds, the study found.
TUC general secretary Frances O'Grady said the UK's "top bosses" are already enjoying a level of pay and bonuses that go beyond "common decency".
"As pensions are not performance-related there can be no justification for this stark divide in company pensions," said O'Grady.
The study showed that rather than exercising restraint on their remuneration packages, Britain's top bosses are simply finding new ways of rewarding themselves.
"Some directors are collecting millions while schemes are scaled back for ordinary staff," said O'Grady.
"For decades, companies have been telling employees that decent pensions are an unaffordable luxury. But these rules clearly don't apply to those at the top."
The new norm
The TUC said it's concerned that cash payments and employer contribution rates to top bosses' DC pensions are being "ratcheted up" in a similar way to their bonuses.
It said for many directors' pensions, and the remuneration committees that set them, a 30% contribution rate is becoming the new norm. This rate increase means that employer contributions, which already go up when directors' salaries rise, are going up far quicker for directors than for ordinary staff.
The TUC is also concerned that while pay and bonuses are now under much closer scrutiny, the complicated arrangements for reporting directors' pensions make it hard for shareholders and the media to find out how much their pensions are worth.
It said it wants to see greater clarity in the reporting of pensions, including the mandatory disclosure of accrual and contribution rates.
