www.loyensloeff.ch/en/news/is-your-lump-sum-taxation-ruling-up-to-date/
See also:
www.iwpx.net/2018/08/28/switzerland-lump-sum-taxation-of-individuals-new-federal-circular-letter/
www.walderwyss.com/user_assets/publications/2230.pdf
Relocating to Switzerland: lump-sum tax regime