I'm currently job hunting. I'm almost 5 years at my current position, by far longer than any other position I had. So I'd improve my chances by having an interim report. Asking my boss for one would be equivalent to letting him know I'm job hunting. I'm not sure if the gain is worth the risk, because I don't know for sure what could go wrong. What could?
My boss may already suspect I look for a new job: I've approached him about a job change within the company a while back without success. Also, the company is in a very bad shape. We recently had a short talk about this, my boss admitted freely that he doesnt know how the future of the company will look like - his words: "We'll probably still exist in a year."
I've read this question and the answers. According to this discussion, the Company may fire me outright to hire and train my replacement earlier.
For about the next half year I'd be pretty hard to fire legally, but it's certainly not impossible. My team is overworked as is and recently one teammember was fired. I don't think my job would be in immediate danger (but could be wrong).
What are other problems I might have when I approach my boss about an interim report?
For the benefit of our international readers: in the German-speaking areas (mainly Germany, also Switzerland and Austria), you are legally entitled to an Arbeitszeugnis if you leave a job. An Arbeitszeugnis, literally "work report card" or "job report card", is a two-page letter that gives the dates of your employment, your duties and an indication of how well you performed. You will enclose previous Arbeitszeugnisse with subsequent applications. An Arbeitszeugnis essentially plays the role of references in the US.
If you are still employed at your current job and have been so for multiple years, your last Arbeitszeugnis - from your previous employer - is multiple years old and does not reflect your more recent experience. In such a case, you can request a Zwischenzeugnis (literally "interim report card") from your current employer, which you would then use in applications along with previous Arbeitszeugnisse.
Arbeitszeugnisse and Zwischenzeugnisse are a fundamental part of the workplace in Germany, with many, many lawsuits especially about how honest an employer can be in assessing your performance. By now, a certain "codespeak" has developed. For instance, your Arbeitszeugnis might say that you "always strove enthusiastically to fulfill your duties" - which you should translate into "strove enthusiastically, but did not manage to". Fun stuff.