The total deficit for defined benefit (DB) schemes reached £710bn on a funding basis by 29 August amid further falls in gilt yields.
PwC's Skyval Index found the deficit grew by £100bn on a funding basis since 29 July, fuelling an increase over the last 12 months of £190bn.
It comes amid separate research finding the total deficit has surpassed £1trn since Brexit. However, this figure is measured on a buyout basis, assuming the majority of schemes will look to offload their liabilities to insurers.
PwC's analysis of the UK's 6,000 DB schemes revealed a stark difference between the three methods of calculating the total deficit, on an accounting, funding or buyout basis (see table).
When assessed on a buyout basis, the deficit reached £1.54trn on 29 August, increasing by £150bn over the month and £600bn over the past year.
However, the deficit is just £490bn when calculated on an IAS19 basis accounting basis, and would have increased by £90bn over the month and £220bn over the last year.
PwC global head of pensions Raj Mody (pictured) said given schemes were in "unprecedented times", the challenging conditions from recent events such as the EU referendum should be expected to continue.
He advised companies and trustees to revisit their approach to risk and re-evaluate whether they have the most suitable measurement of the deficit to decide the most effective funding method. For example they should ask if gilt yields are still relevant when deciding how to calculate and finance the deficit.
"There may be more appropriate measures that are better tailored to a scheme's own funding strategy," said Mody. "I would advocate going back to the main principles of understanding how the deficit is calculated in the first place. This will give a more realistic view for trustees and sponsors helping them to make more effective decisions."
