Is Zakat obligatory on a loan of $1500, which is a debt to be repaid in equal, interest-free, tax-free installments?

This money became yours the moment you borrowed it. If it, along with the rest of your wealth, reaches the nisab (minimum threshold) and a hawl (full lunar year) passes over it, zakat becomes obligatory on it. However, you are entitled to deduct the debt from it before calculating zakat, then pay zakat on the remainder if it reaches the nisab. It is forbidden to open an account in an interest-based (usurious) bank.