For different reasons, you may want to have a standard occupancy for your property for the stated price, but are happy to accept more guests above that number to the maximum occupancy, and charge a fee per person for the extra guests.
Firstly, you need to make sure you have the correct beds set up for the property to match your maximum occupancy. Please see this article for checking these settings:
On the Settings > Properties > Rooms > Setup page, you will find a line in the first section titled 'Maximum guests'. Here you can state your maximum occupancy.
Now we need to state what the advertised rate refers to in terms of the standard occupancy. This needs to be done for your website, and then also for specific channels.
Website:
Click the down arrow next to Prices and choose 'Daily Price Setup' or simply click here:
Click on the edit button for each daily price you have set up (you will need to repeat the process for each one). If you have a standard rate, a weekly rate and a monthly rate, you can choose different daily extra guest charges for the different rates.
On the next screen, under maximum guests, state the number of guests the standard rate relates to. For instance, if your maximum occupancy is 10, but you want the standard rate to be for 8 guests, then enter '8'. Then you can state the charge for a 9th or 10th guest in the 'Extra Person' box, eg. 30 for $30 per extra guest per night. If you want to have cheaper rates for children, you can enter a price in the box below, otherwise leave it at 0. Then press save.
Airbnb:
To change occupancy price settings for Airbnb, go to Settings > Channel Manager > Airbnb > Specific Content. Scroll down to the 'Pricing' section. Change the 'Guests Included' box to your standard occupancy, then add the extra guest fees into 'Extra Person Price' then save.
VRBO/Stayz/HomeAway:
The process is very similar for VRBO. Go to Settings > Channel Manager > VRBO / Homeaway XML > Specific Room Content and repeat the same process in the Pricing Section.
Booking.com:
Booking.com pulls info from your Daily Price Setup. The only thing you need to do is make sure you have set the Pricing Model to 'Per Occupancy Pricing' on the Mapping page if you are charging based on guest numbers/capacity.