بسم الله الرحمن الرحيم
(Fatwa: 1476/1495/L=1/1438)
If, after deducting the amount of debt, you are left with gold and cash in a quantity which makes you sahib-e-nisab, then you will have to pay zakah when one year completes on your nisab. It is not right to make delay in paying zakah after completion of the year. However, if it is impossible for you to pay all the zakah in one time, then you may pay in parts and calculate at the end of the year. However, in case you could not pay the zakah of some years, you can pay it later.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband