What is tax threshold for 68 year old?

I am 68 years of age and live off dividends which are taxed before I receive the money. I have a cottage attached to my house (which I own) which I rent out on short term rentals through Airbnb etc. How much do I have to earn per annum before I would have to pay tax on this added income?

Please read our 2016/2017 Tax Tables to see what income you earn before paying tax.