The amount of money raised through payroll giving has fallen by £21m over the past year despite about 100,000 more people donating through the scheme, according to provisional figures published by HM Revenue & Customs.
HMRC figures show that the total amount raised by means of employees giving through their payroll fell to an estimated £134m in 2013/14 from £155m the previous year.
This was despite a rise in the number of people donating in this way from 1,022,000 in 2012/13 to 1,120,000 last year. The cost to the Treasury of income tax relief has remained stable for three years now at £40m, the data shows.
It is the first time since 2008/09 that the total donated has fallen year on year.
HMRC said, however, that year-on-year data should be treated with caution and was not directly comparable because of changes to data collection methods in 2012/13.
It said that the frequency of data collection had changed from quarterly to annually, and there had at the same time been substantial change in the data systems of some payroll-giving agencies.
HMRC had also made increased efforts to gather complete data from the payroll-giving agencies, accompanied by a more pro-active audit programme, the department said.