Your birth time is in UTC if one of the following conditions is met:
You were born in a UTC timezone: GMT+0 or GMT-0
You have manually calculated the UTC birth time by determining the time zone you were born in, applying the UTC offset and Daylight Savings Time (if observed). In this case, you can check the “Birth time is already in UTC” box.
As a general rule, if you are entering your local birth time (as most do), please leave the “Birth time is already in UTC” box unchecked.