All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
First of all, it should be mentioned that Zakat should be calculated according to the lunar calendar and not according to the Gregorian calendar.
As regards your question, the dollars which you have kept in your bank account until the procedures are finalized are considered your property until you give it to your creditor. When a complete lunar year elapses on this money, you are obliged to add it to whichever money in your possession on which a complete lunar year elapsed, and then count apart the debt which you have. If you have other money which is not liable for Zakat to pay for this debt, then you have to pay the Zakat on all your cash money among which is the 20,000 dollars. What we mean by other money is all your property on which you are not obliged to pay the Zakat, except a house, your expenses and the expenses which you are obliged to provide, until a time when it becomes easy for you (to repay your debts).
If you do not have enough money to pay for your debts, then you deduct the amount of your debt from the total amount which you possess, and then pay Zakat on the rest, if it reaches the minimum amount liable for Zakat.
Allaah Knows best.