Equiniti ICS has reported a drop of 12 per cent since 2008 in the number of employees making charitable donations through its payroll giving services.
The figures are based on a representative sample of of more than 12,000 of the 125,000 employees in the 250 organisations for which the firm manages the payroll.
The results indicate that the proportion of employees taking part in payroll giving fell from 4.3 per cent in 2008 to 3.8 per cent in 2010.
The report says the average monthly donation has fallen from just over £19 per month to just under £14. This equates to an average fall of 25 per cent, with some charities seeing falls of up to 50 per cent.
Alan Foley, director of Equiniti ICS, said payroll giving had suffered because of the recession.
"What is significant, and bodes well for the future, is that employees are not deserting their charities altogether and stopping donations completely," he said.
"Instead they are choosing to cut back, which is much more positive in the long term, because it shows an ongoing commitment, but tempered by short-term personal financial fears."