20mg was the highest dose I ever took. My doctor intended to raise it, but I wasn't showing any symptoms the entire 8 months or so I took it. He had weaned me off Risperdal and assumed I needed more Geodon, but it never came to that.
20mg is the lowest dose they make so to taper I took one every other day for two weeks and then every third day for two weeks.
If I were you I'd probably drop to 40mg for two weeks and then to 20 for two weeks and then every other day for two weeks.
Good luck to you with your taper. Keep us posted!