Zakaah is not due on this money until one year has passed since you acquired it, because one of the conditions of zakaah being obligatory is that the wealth should be in one's full possession, and full possession of this money was not achieved until after you received it; before you received it, possession was not established, you might have received it and you might not have, based on the judge’s decision and whether the company was willing to pay.
The scholars of the Standing Committee were asked about a case where the government delayed paying money to those who were entitled to it for nine years – do they have to pay zakaah on it?
If the matter is as described, they should wait for one year starting from the date when they receive it, then they should pay zakaah on it. There is no zakaah due for the past because they did not have full possession of it. End quote.
Fataawa al-Lajnah al-Daa’imah (9/284).
And Allaah knows best.