.The tax treated as paid is exactly that. You don't have to pay it to HMRC. The following applies to each of yourself and your wife:Take a look at HS320 here. Divide the gain by the number of relevant years as shown on the certificate. Add that figure to your other income /15. If the total is over £41,865 then you need to disclose the gain and you will have some more tax to pay.If you are over state pension age, the gross gain is treated as income purposes of age allowance so you may lose some of your age allowance if your income in 2014/15 including the gross gain is more than £27,000 and you were born before 6 April 1948.I hope this helps but let me know if you have any further questions.