Spain’s tax agency, Hacienda, is introducing new accounting rules for major national taxpayers beginning in 2027. These rules mandate the compulsory application of full International Financial Reporting Standards (IFRS). The change specifically impacts Grandes Contribuyentes Nacionales, or significant national taxpayers. Authorities anticipate this shift will bring increased costs for businesses required to comply. The implementation of full IFRS necessitates more detailed and complex financial reporting processes. This move aims to align Spanish accounting practices with international standards, providing greater transparency. Companies affected should begin preparations now to address the forthcoming financial and operational adjustments.