I am working on a project proposal (DFG project in Germany). I have the problem that I want to calculate how much funds I have to request for my test subjects (e.g., for qualitative interview of about one hour). However, I do not know what hourly compensation rate is the current norm. I have old project proposals as templates. One of them refers to "recommendations concerning participant compensation", however without providing any further information or reference. Also, I cannot simply use the hourly rates used in the old project proposals, because they are more than 10 years old. I have searched the DFG website, but could not find the information I need.

What hourly rates for test persons are acceptable for the DFG in psychological research? Are there any official recommendations that I can cite?

Thank you very much for your help!