There were 97,600 residential transactions in August, 6.1 per cent lower than in the same month last year, when adjusted for seasonal variations.
The figures from HM Revenue and Customs (HMRC) show little change on the number of transactions as compared to July.
HMRC said the introduction of a higher rate of stamp duty on second homes would account for the spike in property transactions in March - and the corresponding lull in April - but said other issues could have also played a role, such as the EU referendum.
Of the 109,630 property transactions that took place in the UK last month, 94,250 were in England.
Jeremy Duncombe, director of Legal & General mortgage club, said it is normal to see a drop in the number of property transactions in the summer months.
"These figures simply reflect this seasonal cooling off period," Duncombe said. "August, in particular, is typically a quiet time for mortgage activity, as many borrowers prefer to focus on holidays rather than house buying."
David Brown, chief executive of London estate agents Marsh & Parsons, said: "The total numbers for the first and the second quarter of 2016 were astronomically high compared to the corresponding period last year. Consequently, the market is still levelling after the frenzy we saw as people clambered to meet the April stamp duty deadline.
"Even if we had not had the referendum vote, we would have expected to spend a good few months seeing the market recover to some level of normality."