Fiscalization in Spain: Is it possible to “customize” POS SW?

In Spain, POS software certified under SIF regulations may be customized without separate recertification as long as changes don’t affect mandatory billing requirements outlined in Royal Decree 1007/2023 and OM HAC/1177/2024. Minor modifications—such as invoice layout tweaks—are allowed under the existing certification, but changes impacting compliance require a new Responsible Declaration.