From full time to part time - help needed with the request

[SnowWhiteisMyFavourite]

I hope someone can help.

I'm due to go back to work in June and now drafting my letter to request to work 4 days a week instead of 5. I'm a manager and my company has an unwritten policy "no part time managers if team is full time".

I'm planning to work from 8.30am to 5pm Mon - Thurs (8.30am to 4.30pm Mon - Fri previously) which probably will mean that I will loose some of my current responsibilities to accommodate this request. I personally feel that I could do my current job (tasks) in 4 days, of course my team would have to cover all urgent things on Fridays but they already do that if I'm on holiday. I guess I would need some kind of "debuty" which I already have but this is not a formal arrangement. So, the guestion is, how should I word this to make sure that they can't refuse my request?

Has anyone been in the same situation and has managed to reduce the hours?

I manage a customer services department and I went from full time to part time - 3 days a week. I am the only pt manager there. Just gave Said basically what yu have written. When I went back I also started training one of my staff and managed to get her promoted to be my deputy which she has been doing since I went on my second lot of maternity leave