Related questions
As long as you are in possession of wealth above the Nisab threshold at the beginning and end of the zakat year, zakat will be payable, even if your wealth dipped below the nisab for most of the year.
I earned a large amount of cash a few days before the zakat year was up, do I pay zakat on this amount now, or after a year has passed from when I received it?
You pay zakat when the zakat year has elapsed, irrespective of when particular portions of your wealth came into your possession. Even if the cash came into your possession a day before the zakat year had elapsed, you would have to pay zakat on it the following day.