Puerto Rico's Treasury Department has published Administrative Determination (AD) No. 21-08 of 20 September 2021, which amends AD No. 21-05 of 11 May 2021 in regard to the general 51% disallowance of deductions for cross-border expenses incurred with related persons not engaged in trade or business in Puerto Rico. AD No. 21-05 provided that the relief from the 51% disallowance is provided when a deduction is supported by a transfer pricing study that has been prepared and is available at the time of filing the tax return, without needing to submit the transfer pricing study with the return. AD No....