Each level of the Addiction quality determines how badly you are addicted.Mild You need to make a Withdrawal test once a month if you have not "gotten a fix".Moderate You need to make a Withdrawal test every two weeks.Severe You need to make a Withdrawal test once a week.Burnout You need to make a Withdrawal test daily.The addiction rating and threshold depends on the addiction (SR5, p. 414), but a Withdrawal test is the same as an Addiction test, but, success means that you can get rid of the addiction. A normal Addiction Test is when you have gotten your fix and failure on this test means the Quality increases in severity without earning Karma from the quality. Hope this helps!