Broadly, if selling a business you want the sale to have as much as possible as good will. If buying, the reverse. You can't depreciate good will and it sits on your books forever (if you're the buyer).
It is taxable, however there are a number of ways to minimise the tax depending on your age, the size of the business and other variables. This is an area where spending a bit of money on quality accounting advice can save many thousands of dollars.
