Welcome to Cornerstone We are a niche firm of tax consultants specialising in advice on Stamp Duty Land Tax (SDLT). We are experts when it comes to property tax matters, advising you on how to arrange your property transaction in the most tax efficient manner. Now in our 6th year, Cornerstone Tax is well established in the industry as market leaders for this very specialist area of tax planning. We provide advice and strategies for clients of solicitors, accountants, banks, wealth managers and trust companies across the UK and internationally.