A tax that is considered fair by most people in a society is where the tax rate is progressive so that the more a person earns the higher rate of tax they pay and on the opposite end of the scale those with low income should pay very little if any. The other very important factor which is involved is is what are the taxes spent on? If they are mainly spent on meeting the needs of the most dispossessed people plus the basic needs of the general society for health care, education and housing then that is very important too.