Hi SGR,
If a third-party is doing your payroll, do you mean you want to record the payment in your books for tracking purposes? If yes and if the repayment is an incoming fund to your business account, you can record it as a bank deposit. However, it's best if you can seek an accountant's advice especially in choosing the right accounts for this record. If no, I'd appreciate it if you can add more details below.
Thanks in advance for your reply.