It's certainly not something you should hide - time taken off sick for stress is just like time taken off sick for another complaint such as a broken ankle or an appendectomy. Sure, it's inconvenient to take that much sick time, but it's a valid reason. I presume that to take off that much time you'd have had a note from your doctor anyway.The way you should phrase it, to be sure of conveying the right message, is to also talk about why you were stressed and what you've done to be sure you don't "relapse". Three weeks of stress sounds (to a non-medically trained ear) like it was pretty serious and not likely to be a one-off event that sorts itself out.You can put people's minds at ease by showing that you have it under control. For example, you might have learned stress control techniques, made a stronger resolve to book and use your annual leave time fully, or learned that you need to ask for support earlier.At the end of the day, starting a new job always has potential to be a stressful event. Your new employer will also expect you to hit the ground running and may push you hard at first to learn your limits. You want to make sure you are ready, putting back your start date if you are not in the right place to go through all that again.
