All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If you paid the Zakat after you obtained some money, then you should wait for one lunar year to pass on this new amount. After the passing of one lunar year, you have to pay Zakat again on the money. Suppose you owned 1200 Dollars in RAMADAN 1419 A.H. When the RAMADAN of 1420 A.H. comes, you should pay 30 Dollars as Zakat from this amount. After five months, i.e., in the month of SAFAR, you gained a new amount of 1000 Dollars, then you have to pay Zakat on this amount in 1421 A.H. in the month of SAFAR.
For more benefit, please refer to Fatwa 82016.
You have to pay Zakat on your money with two conditions:
1-It should complete the Nisaab (the minimum amount liable for Zakat); anyone who has more than this Nisaab is obliged to pay Zakat) by itself or by adding it to other earnings.
2 -One Islamic (lunar) year should pass after possessing the money.
Allah knows best.