Whilst the deficit increased by £29.2bn in December, it fell by £81.2bn in November. There are so many variables that it would be inconceivable for there to be no change during the course of a month. Scheme deficits change for a number of reasons including changes in investment returns and the cost of buying out schemes though an insurance contact. 

The PPF attributes the increased deficits in December to an increase in liabilities, with asset values increasing and gilt yields falling.The PPF always has a clear view of potential liabilities so that even large failures such as the BHS scheme can be factored into its calculations and its plans to ultimately be self sufficient by 2030 through investment of those assets that it acquires when sponsoring companies fail and the PPF levy.