Why do I need a Carnet?
When you must have an ATA Carnet
If you are travelling with professional equipment to a country which takes part in the ATA Carnet system, you must have a Carnet
A carnet is an international shipping document that allows you to leave your home country, enter another for filming or other purposes and come home having exported and imported your equipment as often as you like without the need to pay import duty or tax.
Not having a Carnet can cost you money
Whilst you are free to travel without a Carnet, it's extemely inadvisable to do so. You may well be stopped by customs as you enter your destination country and you will probably be charged import duty at a set percentage of the equipment's value. Given that a shooting kit can run to in excess of GBP 100,000 , paying a percentage of this to customs would be a serious set back to your budget or credit card. You would also have to fill in a number of forms which would in theory allow you to reclaim this money when you leave the country. The whole process would be time consuming, messy and potentially very costly.
How the Carnet avoids you paying import duty
Having a Carnet basically allows you to prove to customs that the equipment has not been sold in the country you are visiting and is therefore free from import duty. It lists all the equipment and shows that you have returned all the items to your home country and that nothing has been left in any of the countries you have visited on your trip.