The European Union Horizon 2020 grants program has published guidance for awardees, How to Avoid Errors When Claiming Costs in H2020 Grants. The document lists the most common errors along with some explanations.
Additional grant management resources are available on the Participant Portal H2020 Online Manual website. Topics include keeping records, amendments, reports and payment requests, deliverables, dissemination and exploitation of results, communicating your project, and checks, audits, reviews and investigations.