Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Any amount of money that has been in your possession for one lunar year and its value equals the value of 85 grams of gold is subject to Zakah.
As for any sum of money that you deserve but have not received, your duty is to pay Zakah for every year if such money is required from one who is rich and able to pay. But, if such money is required from one who is unable to pay or procrastinating, then you are to pay Zakah when you receive money.
So, our dear inquirer has to base his decision depending on the above-stated examples.
Allah knows best.