“Don’t save,” say the governments of rich countries as they worry about demand in economies that are hovering between sluggish recovery and recession. Their injunctions are aided and abetted by central banks, which are keeping interest rates negative in real terms (ie, after inflation), a policy that transfers wealth from savers to borrowers.

“Save,” say those same governments as they contemplate the ageing of their populations and the potential strain on the public purse. As encouragement, they offer tax breaks to those who put money aside to fund their retirement.Pension funds are caught in the middle of these contradictory messages, and they are suffering. In Britain the Pensions Regulator, which oversees corporate schemes, recently relaxed its guidelines to help funds that are heavily in deficit.

The same policies that have forced down government-bond yields have forced up the cost of providing pensions. Offering a pension is like incurring a debt, since it involves the promise of a series of future payments. When pension funds calculate the value of their liabilities, they therefore use a bond yield to discount future payments. As bond yields fall, the liabilities rise.

This is not just a theoretical issue. It is possible for British companies to offload their pension liabilities to an insurance company. The insurance company largely funds such pensions by buying government bonds. So getting rid of the pension promise has become more expensive.