REFORMING STAMP DUTY – A TAX CUT FOR 98% OF THOSE WHO PAY STAMP DUTY. The slab system distorted the market with big jumps in taxes when house values climbed into a new band. Our new slice system will work like income tax, so you only pay the higher rate on the part of the property that falls within that band. 98% of buyers who pay stamp duty will pay less. The buyer of the average family home (worth £275,000) will pay £4,500 less. Of people who pay stamp duty in London, 91% will pay less. This is a tax cut of £800 million a year.