Hi, we have a simple s corporation in Ca. What do we need to do to add several other business concepts to our corp. umbrella?

As long as the new concepts are legal, generally you should be able to start offering them without issue. This may not work in all areas, such as professional corporation. You should seek counsel regardless, as this could get into licensing or trademark issues very easily.

An online forum may not be your best resource to get quality information, as attorneys do not have ample time to learn about your particular company, or to review applicable law in your case.

I am not your attorney. The information I am providing is merely educational in nature.

If they have the same liabiity risk level (likelihood of being sued), then put each entity into a S corp subsidiary that must be incorporated (called QSubs). If the risk level is the same, you can aggregate them into one so long as you accept the risk of exposing all of the other business ideas to the risk of loss. You roll the dice.

The best way is to set up a Series LLC and park each "business concept" into a series. California does not have a series LLC statute. You'd have to use another state's and then qualify the seriess LLC in California as a foreign legal entity.

You should speak to a competent tax/corporate attorney before doing this. It's a bit complicated as you can see.

Good luck.