The best time to take a daily vitamin D supplement is in the morning, before going out into the sun. But your body produces most of its own vitamin D when you expose it to sunlight. That means that even if you don’t go outside on a regular basis, you can still get some natural vitamin D by exposing parts of your skin where there are fewer rays coming through (for instance around your eyes and face). This exposure may be enough for your body to make some “fake” vitamin D (called calcitriol), which also helps with calcium absorption. The most effective way to do this is simply sitting in front of an artificial light source like an LCD computer monitor or TV screen for long periods during the day (20 minutes at least three times per week). You can read more about this exposure here: https://www.vitamindcouncilsolutions.org/blog/?p=4483&lang=en#more-4483 . When taking multivitamin supplements containing Vitamin D3 , these doses will not typically contain much synthetic form of Vitamin A or beta carotene so they shouldn’t interfere with absorption anyway!