NiSi announced a new Filter Holder for the new Sony FE 12-24mm lens. You can buy it now at Amazon US and Amazon DE. And Fred Miranda found a even cheaper way to be able to use filters on your Sony 12-24mm lens:
I just tested a way to use regular filters (77mm) on the Sony FE 12-24/4 G ultra wide. It won’t vignette from 14mm until 24mm making this lens even more versatile now. It’s possible it will work with polarizers as well. That will save many photographers from carrying huge 150mm filters and adapters to use with this lens! 😉
Sony FE 12-24mm f/4 G with 77mm regular filters!
http://www.fredmiranda.com/forum/topic/1503152
Sony 12-24mm store links to [shopcountry 60621].