I want to know about whats the procedure to calculate and to pay khums? I am doing a job and getting monthly salary, as I am single so I am trying to save most of the money for future and other purposes. Please tell me how can I calculate my khums from my salary? Moreover, apart from salary on which other items do we need to pay khums? Please guide me. I may want to add that the savings I am doing is to pay installments quarter wise for my plot which I bought.

Khums is applied on saving and first you have to fix a date and you may pay early on that date whatever left consider as saving and whatever from grocery and items are unused have to calculate the value and add that amount and gift which was not used add the value with saving and pay 20% of the whole half is sahme imam goes to your marja or representative and half is sahme sadaat goes to poor needy practicing Sadat (Syed) .
Yes it is right for future you are saving money but you have to pay khums on that saving. On instalments there is no khums it is your expense of the year.