Watson Wyatt calculated the figure using FRS 17 which is the new accounting standard which all listed companies must use from 1 January 2005.
It is 50% higher than government estimates, and dwarfs the national debt which currently stands at £400bn.
Public sector pension liabilities are now growing at a rate of £46bn a year, enough to add 14p to income tax, the Daily Telegraph reported.
Last week actuaries Lane Clark & Peacock calculated that the deficits of FTSE100 pension schemes dropped last year from £55bn to £42bn.
FRS 17 requires businesses to show pension fund assets and liabilities on the balance sheet for the first time.
Does Darwin's theory apply to taxation? Colin ponders...
The EC has been instructed to draft a European Union (EU) directive authorising an EU financial transaction tax, which would apply to ten of the EU’s 28 member states
Accountancy watchdog the FRC has dropped its investigation into the former chief financial officer of Tesco, nearly two years after the supermarket was engulfed in an accounting scandal
Colin imagines how Apple's logo might change in the wake of the EC's ruling over its Irish tax arrangements