The Government has approved proposals for changes to the Ireland/United States Preclearance Agreement at Dublin and Shannon Airports.
The changes relate to how additional and enhanced preclearance services will be paid for.
They were approved after an agreement was reached between Irish and US officials, following detailed negotiations.
The amendments allow for reimbursement by airport authorities of the costs of additional and enhanced services.
The Government has said costs associated with the additional services will be "substantially paid for" by Irish airport authorities.
While US authorities will continue to fund a baseline level of service, on a par with what is currently offered.
The amounts to be paid will be set out in Memoranda of Understanding between US Customs and Border Protection and each airport.
The additional costs will be borne by those using the services, and will not be a charge on the exchequer.
A sign for US Preclearance at Dublin Airport | Image: Dublin Airport
However it is not proposed to fundamentally change the operation of preclearance in Ireland, or to give any additional powers to US officials working at Irish airports.
US Preclearance is carried out by officers of US Customs and Border Protection in Dublin and Shannon, under the terms of an international agreement.
The preclearance facilities are within Irish jurisdiction and under Irish law.
US Customs and Border Protection officers are not equipped with firearms, and are not considered to be law enforcement officers in Ireland.
The revised agreement will come into effect in the coming months.
Tánaiste and Foreign Affairs Minister Simon Coveney said: "US Preclearance is a major asset for Irish travellers and a big draw for airlines to route tens of thousands of passengers through our airports every year.
"We are one of the very few countries to have it, so seeing the system expand in Dublin and Shannon is a very welcome development."
Some 1.7 million passengers used the service in 2017.