Can I set a credit limit for my sub agents so they can book now and pay me later without going over what I allow?

Yes, this is a standard part of most travel back office systems, and it is one of the main reasons agencies move away from tracking agent balances in spreadsheets.

The usual arrangement is that every sub agent has their own account with a wallet or a running ledger. You decide the credit you are willing to give each one, and you can set it differently for an agent you have worked with for years and one who has just signed up. When that agent makes a booking, the amount is held against their balance straight away. If the booking would take them past the limit you set, the system stops it at the payment step, or holds it for your team to approve, rather than letting it through and leaving you to chase the money later. When the agent pays you, by bank transfer, card or cash at your counter, your staff record the receipt against their account and the credit becomes available again.

There are limits to be honest about. The system can only hold back a booking it is actually processing, so if an agent calls your office and your staff book manually outside the platform, that will not be caught unless it is entered in. Some suppliers also take payment from you at the moment of ticketing rather than later, so your own cash is committed even though your agent has not paid yet, and that is a commercial risk no software removes. How much of the control you get also varies with the plan you are on.

Before you set this up, work out what credit each of your agents should really have and how you want the system to behave when they reach it, blocked outright or sent to you for a decision.