My basic salary is R18,500 per month. My company pays my full medical aid for myself and my 2 kids. The total paid to Discovery is R4,517.00 per month. The portion added on top of my salary to be taxed is the amount of R3,470.00 (Difference of R1,047 from full amount). So Taxable amount is R21,970.00. What I would like to know is how do they get to this R3,470.00? What is the formula to calculate what portion of your medical aid is taxable every month?