Does a woman still have to do Iddat for 3 months if she has been separated from her husband for 8 or more months?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If what you mean is separation without divorce, then this by itself is not considered a divorce, so it does not necessitate Iddah (waiting period) regardless of whether the period of time is long or short. The bond of marriage is still ongoing between both spouses until divorce takes place. As regards a mere separation, it does not eliminate the bond of marriage between them.

It should be noted that there are many kinds of waiting periods; it differs according to different women. Some women observe their waiting period by months, such as young girls and women who have reached menopause, and some women observe their waiting period by menstruation, who are the women who have monthly menses. Some other women observe their waiting period by giving birth to the baby, who are pregnant women.

For more benefit, please refer to Fataawa 82732, 89825, 145179, 81633 and 81716.

Allah knows best.