Can I use 12/3 for two circuits?

[Photographer]

I am adding some lights and receptacles to my 1978 California home. The original wiring contains several runs that use 12/3 Romex to supply two circuits from two breakers in the panel. For example, the lights in the kitchen are on the red/white circuit and the outlets are on the black/white circuit. Is this still an acceptable practice? Do I need to de-rate the circuits because they use a common neutral?

Many thanks.

[imported_joed]

Perfectly accetable and still done today. No need to derate.

[Photographer]

Great - that's one fewer runs of 12/2 that I have to route through my attic crawl space.