You can find general policy covering administrative representatives in Notice 550 Air Passenger Duty.
You should review the amount of security on a regular basis and may increase or decrease the amount required. In doing so, you must take the following factors, in particular, into consideration:
Unless the aircraft operator intends to operate a single flight
or unless their anticipated APD liability is very small, they must
provide security in the form of a written guarantee from a
financial institution (usually a bank) which is acceptable to us.
Please see APD13700 for an acceptable form of words for the
guarantee. The CAT is able to confirm whether a guarantor is
acceptable.
The aircraft operator, or their representative, must arrange
for the guarantee, duly authorised by the guarantor, to be sent to
the CAT within the time limits set out in
Notice 550 Air Passenger Duty.
If however, the aircraft operator’s estimated APD
liability for the 5 month period is less than £10,000 or they
intend to operate only one flight within the next 5 months they
may, instead of providing a guarantee, lodge with us either a sum
of cash or a bankers draft equal to the value of their estimate.
The written guarantee or cash deposit/bankers draft must be
accompanied by a statement from the aircraft operator that the
amount of the guarantee is a true estimate of their liability and
that they have exercised due care and diligence in making it.