There are several options in the current management systems that allow you to track and pay out (to producers or otherwise) on commissions as a percentage of the commission that the agency receives.
As you mention, some companies do offer direct bill commissions download which will automatically create entries based on the commissions that the carriers are paying.
However, to be able to run production reports and see how much needs to be paid involves invoicing each premium-bearing transaction and subsequently a decision on whether to reconcile these transactions once the companies' pay commissions (some agencies do not feel the time/effort involved to do this second "step" is a value add).
Some of the management systems also have functionality that will assist in the creation of invoices based on the premium amounts for each transaction that is downloaded (obviously won't help if the company doesn't at least download).
Either with this functionality or manually invoicing each transaction (as a step in the workflow) you will have what you need to be able to pay your employees a percentage of the commissions. Again, whether or not you reconcile (or have direct bill commission downloads set up) to "close the loop" on the commissions paid out versus what you receive from the companies is a business decision you can make.
As a side note, most systems these days have a very easy invoicing function and as long as account managers/CSRs are trained how to, and the expectation is set that they will, invoice each premium bearing transaction, commissions are not difficult to track.
Regards,
Jason
Jason@bhbco.com