Minimum requirement :

Define a commission rate attached to a TA (see possible rules, but at least a % on room rate or total stay) 
Attach or detach automatically (OTA) or manually a TA to a reservation  
Calculate and store TA commissions  
Reports (statements)

Description:

Things to know about travel agent commission management
Reservations are linked to an agent with a specific commission calculation configuration.

Reservations may be linked to a travel agent in order to attribute the business brought, but you may ask PMS not to calculate the commission of specific reservations, if needed.
There is a procedure to follow for commissions that are withheld at the source.
Travel agent commission is calculated at the night audit following the guests' departure, and is recorded in the GL transaction table (transaction type = "Travel agent commission"), and is inscribed in the "Commissions" tab of the respective travel agency.

Commissions are calculated based on:

The travel agent configuration
The dollar value and length of the guests' stay
If the commission is taxable or not
If the commission is applicable on rate or/and Products

When you print cheques from Hotello or issue commission cheques from your external accounting system, you will indicate in PMS which commissions have been paid, thus keeping the list of outstanding commissions current.

Security settings can be imposed restricting access to travel agent functions.
The travel agent are send from Channel manager with or without the option to create the new one.

Problems we are trying to solve:
Commissions may be adjusted in the event that they are calculated erroneously.
Taxes may be added to an agency's calculation commission to arrive at a total amount payable.
Travel agent account statements may be printed in the reports menu. These are useful for reconciling commissions or attaching as an explanation with a commission payment.
PMS is able to print your commission cheques (and in the currency of your choice with Foreign currency module) or other payment (Sepa per example) .