QES (qualified electronic signature)

The highest signature level under eIDAS: an advanced electronic signature created with a qualified signature creation device and based on a qualified certificate issued by an approved trust service provider. A QES has the same legal effect as a handwritten signature throughout the EU and is recognised across member states. It is only required in special cases where the law imposes formal requirements — for ordinary business agreements, an AES or SES is usually sufficient. In return, the burden of proof is effectively reversed: with a QES, the party disputing the signature must prove it is not genuine.