A total of 98,540 homes were sold in May, seasonally-adjusted figures from HM Revenue and Customs (HMRC) show, down 3% on a year earlier.
The first nine months of 2014 saw property being sold at the fastest rate since before the financial crisis.
Other data has predicted a modest pick-up in the housing market during the latter half of this year.
The HMRC figures cover properties sold for more than Â£40,000 across the UK.
Some 1.7 million homes were sold in 2006, at the height of the property boom. This fell to 848,000 in 2009, but rose to 1.2 million last year.
In recent months sales have fallen back to below 100,000 a month.
Recent reports from the mortgage market - a precursor to sales - have suggested that there is likely to be a modest increase in activity later in the year.
Gross mortgage lending rose by 2% in May compared with April to Â£16.2bn, according to the Council of Mortgage Lenders (CML).
Property commentator Henry Pryor said he saw evidence of pent-up demand.
"Buyers have been sitting on their hands. Prices peaked in the first half of last year and, while asking prices have picked up in recent months, sale prices will continue to come under pressure," he said.
Property sales data has provided more evidence that the UK housing market is moving more slowly than a year ago.