Visitors from Ireland and 35 other nations travelling to the United States will have to pay about €10.50 ($14) to apply for permission to enter the country from next month.
The fee is being levied for all passengers using the compulsory Electronic System for Travel Authorisation (Esta), the online approval sch- eme that will eventually re- place green visa-waiver forms.
Prospective visitors must pay a $14 fee from September 8, part of which will go to a fund to promote tourism.
Esta applies to nationals of the 36 countries, mostly Western states, who are able to enter the US as tourists without a full travel visa.
Visitors to the US who need a full visa pay a fee starting from $140, depending on the nature of their trip.
An approval from Esta is valid for two years and can be used for repeated visits.
One consumer expert has urged anyone considering a trip to the US to apply for a form now in order to avoid the charge.
He said: "The security authorisation lasts for two years, so do it now and it'll be free if you travel in that time. Yet leave it for a month and you'll have to pay for it."