CML analysis shows that, after the previous stamp duty concession that ended in December 2009, the spike in sales of exempted properties that had pre-empted the end of the concession was matched by a corresponding slump.
HM Revenue & Customs is due to publish an impact assessment of the current concession this autumn, but the CML believes that its withdrawal could distort the pattern of monthly transactions in a similar way to the ending of the previous concession.
This would be unhelpful, given the fragile state of market confidence.
The CML believes that there continues to be a good case for fundamental reform of the "slab" structure of residential stamp duty, and has long advocated a move to a marginal rate system similar to income tax.
But this is a longer term objective, and less pressing than the need to avoid short-term negative effects by removing the first-time buyer concession.
The concession itself is likely to be costing the government only a modest sum in foregone revenue as a result of the relatively low number of transactions in the market at present - and it was, in any event, a stated intention (albeit by the previous government) that the cost of the concession would be offset by the new permanent 5% higher rate of stamp duty on properties worth more than £1 million, which took effect at the start of the current financial year.
The lion's share of residential stamp duty yield - 87% - comes from sales of properties of more than £250,000 value.
In absolute terms, the revenue from stamp duty has fallen markedly from a peak of £6.7billion in 2007-8 to just over £4 billion in 2010-11, but it would rise only modestly if the concession is allowed to expire as planned, since low transaction numbers are the primary reason for the decline.
