What tax if any will i have to pay if isell my second property, if so is there any way around not paying?

I purchased a second property for my mother to live and she pays me rent to cover the mortgage only, if i sell the property in the future what tax will i have to pay, are there any ways around not paying tax. the mortgage is in my wife and i name with the condition a dependant reletive is living there, it is not a buy to let mortgage.
Answer
The amount you will have to pay will be 40 % of the gain less your capital gains allowances accumulated over the years. so the longer you have held the property, the greater the allowance. you can also take into account sale and purchase expenses.