How do I get an A1 certificate?

The employer and the travelers themselves are responsible for applying for the A1 certificate. The contact partner for employees with statutory health insurance is their health insurance company, for privately-insured/civil servants the German Pension Insurance (Bund).
The application for the A1 certificate must be made via the Human Resources Division of the CAU from where it will be forwarded to the DLZP or the pension insurance institution. The traveler must complete one of the following forms at least three weeks before the start of the trip - depending on the health insurance status - and send it to the relevant employee at the Human Recourses Division of the CAU:

a)    Persons with statutory health insurance when travelling in the EU-/EFTA-area

b)    Privately insured persons travelling in the EU-/EFTA-area

Persons with statutory insurance are requested to send the completed form for travel to EU or EFTA countries by e-mail to the person responsible in the Personnel Department (R12). Those with private health insurance should send the form by e-mail to the Civil Service and Appeals Department (R11).    
Information on how to fill out the application forms can be found here (german only)
As soon as the requesting body has received the certificate, it shall be sent to the traveler by post or e-mail.    
Business trip applications and approvals will be made separately and as up to now, in good time before the start of the trip using the online procedure 'WinTrip' of the Travel Expenses Department (R14).