Islam and the Quran

I subtract my salary from my wealth to calculate zakah. Is it right?

Question: I have 20,000 € cash that brings income and I have 700 € salary. I multiply my salary with 12 and come up with a yearly subsistence of 9,000 €. I subtract this amount from 20,000 and give one fortieth of 11,000 as Zakat. Do I make it right, or what is the right way?

You salary is already your subsistence. You need to give one fortieth of 20,000 as Zakat.