A turnover rate needs a stated population, period and denominator. These tasks define attrition as period terminations divided by average beginning and ending headcount, multiplied by one hundred. Beginning headcount means the day before the period starts. The dates are inclusive for the exit count.
Count the exits from All Workers so a current-only source can't remove the numerator. Then compute both headcount snapshots using employment dates. An organization can have no exits and still have workers, which gives zero attrition under this definition. A period with no workforce has no exposure; this simulator reports zero for that denominator boundary and labels the convention in the task. Don't assume another employer uses the same measure merely because it has the same title.