In his December announcement the Scottish Finance Secretary added an additional 3% Land and Buildings Transaction Tax on all second residential property transactions over £40,000 from April 2016.
This means that any Buy To Let property that completes after 1st April will be liable for this tax on top of any other LBTT tax that is due.
This does however give 2 ½ months to increase your portfolio and avoid the new tax. With interest rates on Buy To Let Mortgages currently as low as 2% (typically around 2.5%) buy a rental property is unlikely to be as affordable in the foreseeable future.