The tax information exchange agreement between Guernsey and Portugal will enter into force on 16 March 2018. The treaty, signed 9 July 2010, is the first of its kind between the two countries. It applies for criminal tax matters on the date of its entry into force and for other matters in respect of taxable periods beginning on or after that date or, where there is no taxable period, all charges to tax arising on or after that date.