Customs inspectors have tightened border checks in the run-up to Christmas to ensure holiday shoppers pay duty on goods bought in Spain.
Anyone caught dodging the rules faces a fine and even a court appearance.
The move has helped address concerns long voiced by local retailers, many of who say they are not competing on a level playing field with shops in Spain.
In an official statement late last month, Customs said: “In the run up to the festive season, Customs are reminding the general public of the obligation to declare on importation all dutiable goods that have been obtained outside Gibraltar.”
A simplified personal declaration form was made available to people crossing into Spain to speed up the customs clearance process.
Local travel agents organising shopping trips were briefed on the procedures and followed and provided with the forms.
“Failure to declare any goods will result in court procedures or fines being imposed,” the official notice warned.
As this edition went to press, there was no information available as to how many people had fallen foul of the tightened checks.