Travellers who do not receive travel authorization prior to their departure may be denied boarding, experience delays or be denied admission into the United States. Applications may be submitted at anytime prior to travel, but no less than 72 hours prior to departure.

Travel Authorization is obtained through an online registration system known as the Electronic System for Travel Authorization (ESTA). While not compulsory, travellers may obtain travel authorization from August 1, 2008 onwards. If you are planning on travelling to the United States anytime after August 1, you may wish to consider registering with ESTA before your departure. If your registration is successful, it will be valid for multiple applications for two years or until the date on which your passport expires, which ever comes first.

Before going on line to register, you should ensure that you are qualified to travel under the Visa Waiver Program (UK passport holders are qualified) otherwise your registration will be rejected. ESTA only authorizes a traveller to board an air or sea carrier for travel to the United States. It also does not guarantee entry into the United States; that decision rests with the immigration official at the Port of Entry in the same way that travellers currently entering the U.S. under the Visa Waiver Program or with a visa are subject to inspection.

Submit your ESTA Application at https://esta.cbp.dhs.gov.