Critical illness cover has some similarities to life assurance, the big difference being that it becomes payable if you’re unlucky enough to be diagnosed with one of the illnesses mentioned on your insurance policy. This is usually given as a one-off, tax- free lump sum designed to pay off your mortgage and cover any other expenses you may incur. Like life assurance, it’s a must-have if your family depends on your income to keep a roof over their heads and maintain a reasonable standard of living.