There are certain practicalities involved in obtaining an ATA carnet. You should be aware that:
the standard service takes 24 hours, so you must apply in advance, although an express service may be available
there is a charge for issuing a carnet
you need to lodge security to the value of the highest possible amount of duty payable
the way carnets are issued varies from country to country - in the UK, they are issued by chambers of commerce
If applying through the London Chamber of Commerce and Industry (LCCI), the fee payable will depend on whether or not you are a member and whether or not you want express or normal (24-hour) turnaround. Find an export documentation price list.
ATA carnet application
Before you can apply for a carnet you need to know:
exactly what goods are going to be used
who is going to be the named holder
exits from the European Union which countries the goods will be used in and which countries the goods will transit
Who can use an ATA carnet
Although the carnet will name one person as the holder, any authorised person can also use the carnet, if you:
specify 'the holder plus any other authorised person' when applying for the carnet
provide any such authorised people with an appropriate letter of authority on headed paper
Lodging security when applying for an ATA carnet
Although an ATA carnet means you don't need to pay duty and VAT each time the goods cross a border, when you apply for the carnet you do need to lodge security with the issuing association to the value of the highest amount of duty and tax that would have to be paid on the journey if the goods were not re-exported at any point. You can do this in cash or by other payment, or through a variety of indemnity and insurance schemes.
For UK issued carnets, a Carnet Indemnity Scheme is operated by the LCCI. You pay a premium which is based on a percentage of the value of the goods, rather than having to lodge security for the entire amount of any potential duty payable.