The rules on international hiring-out of labour described in this guide apply to contracts entered into after 19 September 2012. For contracts entered into on 19 September 2012 at the latest, the former rules apply until the contract expires, however not beyond 1 October 2013.
Hereafter the rules described in this guide apply. The former rules are described in the previous edition of this guide:

International hiring-out of labour

Employees living in Denmark and having an employer abroad who hires them out to a Danish enterprise cannot use the rules on international hiring-out of labour. The Danish enterprise that has hired them must withhold their tax according to general Danish tax rules.

Danish enterprises hiring out Danish employees to enterprises abroad are referred to in the guide:

Skatten - ved arbejde i udlandet (Taxation - when working abroad). Please note that the guide is only available in Danish.