Taking supplements without assessing what your current daily intake of Vitamin D is can be dangerous; it is surprisingly easy to go over the recommended dosage, and there is such a thing as overdosing on vitamins [1]. You don't just get Vitamin D from the sun - it is also present in eggs, some seafood, and certain fortified dairy products. Because of this, you may not need to take a daily supplement at all. Programmers are at an increased risk for vitamin D deficiency, but you should ALWAYS examine your diet to assess your current vitamin D intake before deciding to take a supplement.
[1] http://www.consumerreports.org/cro/magazine/2012/09/10-surpr...