Spain has published Order HFP/999/2023 of 28 August 2023 in the Official Gazette, which amends Order HFP/308/2023 of 28 March 2023 on the new revised Form (Modelo) 604 for Financial Transactions Tax (FTT) self-assessments. Form 604 was originally approved by Order HAC/510/2021 and is due by the 10th to the 20th of the month following each monthly settlement period. Order HFP/308/2023 revised Form 604 and was to apply for monthly settlement periods beginning on or after 1 September 2023. Du…