This document summarizes the key policies and requirements around open science in Horizon 2020 and Horizon Europe research funding programs. It outlines that Horizon 2020 made open access to publications mandatory and launched a pilot program for open access to research data. Horizon Europe will continue and strengthen these policies by making open access to research data the default, requiring data management plans aligned with FAIR principles, and potentially including sanctions for non-compliance. Open science practices will also be more embedded and promoted throughout the research process.