Airport retailers in Ireland can make VAT savings based on information obtained from passengers' boarding cards.
Despite there being no legal requirement to examine boarding passes, both daa-operated outlets and independent retailers at Dublin Airport regularly do so.
One reason is that certain retailers can claim VAT savings where duty-free purchases are made by passengers travelling outside the European Union.
These account for around 19pc of passengers at Dublin.
"It is policy in our stores to ask that passengers present their boarding card when making a purchase," a spokesperson for Dublin Airport confirmed.
However, the airport insisted that all savings in its stores "are passed on to all passengers" in the form of "key product discounts".
Confusion has surrounded the scanning of boarding passes since reports revealed UK airport retailers have failed to pass on tax savings to customers.
The reports have prompted a consumer backlash, with passengers taking to social media to vent their frustration.
I’m certainly not showing my boarding pass to airport retailers. What message must this send to tourists? Rip-off Britain?— Chris Bryant MP (@RhonddaBryant) August 12, 2015
In Ireland, industry sources have expressed concern that a mass withholding of boarding passes at retail outlets could lead to price rises at airports.
Boarding passes in the spotlight
Boarding passes are scanned by outlets operated by ARI (a subsidiary of daa) for several reasons, the Dublin Airport spokesperson said.
They include improving the airport's stores and retail offering by tracking purchases, assessing new routes and planning staff rosters.
No personal passenger data is gathered or retained in the process.
It is not compulsory to present the cards.
"If any passenger buying a non duty-free product does not wish to provide this information, we will still make the sale," it was confirmed.
Passengers wishing to purchase duty-free alcohol or tobacco are still obliged to prove that they are travelling to a duty-free destination, however.
Retailers are also required by the Revenue Commissioners to retain evidence of passengers travelling to non-EU destinations "such as boarding pass and flight details", it says.
"They must retain this detail in electronic format for future examination, if required."
Airport retail outlets can only apply the zero VAT rate to passengers travelling outside the EU if they complete a Revenue vetting and approval process.
Revenue can't comment on "the commercial pricing policies of individual retailers," but it does "monitor these businesses on an ongoing basis," it added.
Meanwhile, WH Smith has confirmed that scans are "a request, not a demand" at Dublin Airport.
"There is no obligation on the part of the customer," it said in a statement.
"VAT relief associated with the identification of customers travelling outside the EU is reflected in our single price and extensive promotional offers provided to all customers."
Ireland's Competition and Consumer Protection Commission urged all retailers operating in Irish airports to be very clear with their customers as regards the circumstances where they collect VAT on behalf of the State or where VAT is not charged.
"Consumers should also be advised of the reasons why boarding cards are requested when making purchases in Irish airports," it added.