Is the remaining amount from the price of the land considered a debt, or is Zakat obligatory on it?

The remaining amount of the land's price is a debt upon you. According to the majority of scholars, it is deducted from the wealth on which zakat is obligatory. However, according to the Shafi'is, it is not deducted. Some of them stipulate that one should not have non-zakat-able wealth exceeding their needs to offset the debt; otherwise, all the wealth is subject to zakat. This is what we prefer.

If you have non-zakat-able wealth exceeding your needs, use it to offset the debt, then pay the zakat on your wealth. If you do not have excess wealth, zakat is not obligatory if the debt equals the wealth you possess or reduces it below the nisab.

There is no difference between a due debt and a deferred debt, except for a narration from Ahmad which states that only a due debt is deducted.

The nisab for banknotes is the equivalent of 85 grams of gold or 595 grams of silver, and the zakat is a quarter of a tenth (2.5%).