The City of Cologne charges a tax called Tax for the promotion and advancement of culture for every visitor with accomodation within the city.
The Tax is calculated after other taxes in your accomodation pricing and is set at 5%.

As an example:

ITEM	AMOUNT
Assumed net price (excluding tax for the promotion and advancement of culture)	EUR 100.00
7% value added tax on accommodation	EUR 7.00
Assessment basis (net price plus 7% value added tax)	EUR 107.00
Tax for the Promotion and Advancement of Culture (5% of the assessment Basis)	EUR 5.35

 

If you are required to attend EUROMIT 2017 and/or visit for business reasons, you can be exempt from this tax.
All necessary information can also be found on the FAQ of the City of Cologne Tax Agency.

To not be charged with the Tax when you check out of your Hotel, you have to fill in an official form and print it out. Your employer has to sign this form as well. You can then hand in the form at the Hotel reception before you check out.
Your employer has to sign the form where they see fit. It is recommended to sign to the right of the employer's name field (see screenshot below).

You can find the form on the offical Website of the agency. Only this form is accepted, you can not create your own.

Please note: You can only be exempted from this tax if you are required to attend EUROMIT 2017. If you visit Cologne voluntarily, you are required to pay it.