The research showed a gradual increase in deficits, peaking in July just short of £600 billion before dropping.
However, deficits again increased by £100 billion in the last quarter of 2012.
Xafinity corporate solutions director Hugh Creasy said 2013 would be an equally difficult year, with careful consideration of assumptions needed.
He added: "While discount rates for the more mature schemes may be falling to around the 4.5% mark, the discount rate of around 5% can be justified for many.
"An increase of just 0.5% may not sound much, but this would slash the liability measure by 15% – enough to remove the deficit on the balance sheet and wipe out pension charges in the profit and loss account.
"Recent mortality data also offers schemes some leeway in terms of predictions with the news that mortality rates in 2012 were actually 1% higher than the previous year. Direct recognition of the experience in just one year will not have much of an impact, but if it tempers the allowance built into actuaries' projections over the decades to come, the effects will be warmly welcomed by finance directors."
