The British taxman has gained some £136m as a result of cracking down on buy-to-let landlords.
Tax investigations into possible underpayments of capital gains tax for 2013-14 have brought in record amounts, resulting in a 24% increase from the £110 million collected last year.
Last August the taxman sent 40,000 letters to landlords it suspected were not paying enough tax, reminding them of the risk of large fines and criminal investigations if their affairs were not correct.
It appears that HMRC has devoted more resources into its scrutiny of owners of buy-to-let properties, in part because of the rapid rise in property prices which have given investors greater profits in recent years.
Changes to tax laws relating to second properties has been another driver of HMRC’s interest.
Fewer than 500,000 taxpayers are registered with HMRC as owning second properties, but HMRC estimates that the number is around 1.5million.
Overall, the taxman has been taking more capital gains tax as both shares and property prices increase.
According to the latest figures from the Office for Budget Responsibility capital gains take for 2012-13 was £3.9bn. It is estimated to rise to £6.7bn in 2015-16 and reach £9bn by 2018-19.
A spokesman for HMRC said: “Our enquiries are extremely effective as these figures show.”