If your therapist knows you very well, he or she will decide what kind of threat is considered life-threatening. For instance, if you have a history of SI'ing so bad that you needed to go to a hospital or otherwise die, and threat to do the same, your therapist has the obligation to report. However, if you SI normally without needing stitches or otherwise life-saving treatment, and say you are going to SI, your therapist will probably not report you. I have a current therapist who says she will not stand in the way of me SI'ing, but would rather me talk about what is bothering me instead. Therefore, it really depends on your history, what you are threatening, and how well your therapist knows you.