The bathtub requires 2 20amp circuits. One for the pump and the other for the heater. I am going to install a 2 gang box with 2 gfi receptacles. Can I run 12-3 wire and have the 2 GFI breakers share the same neutral wire?

Thanks for your help

No shared neutrals with GFI devices because the neutral current is measured and compared to the current that flows in the hot wire, and trips if there is a difference.

You mention GFI breakers and receptacles, this is not necessary to protect GFI receptacles with a GFI breaker. Use either one or the other, but not both.

If you use standard breakers you can use #12/3 up to the GFI receptacles, then, only 2 wire from each load side to the motor and heater.

Shared neutrals are still allowed, but becoming a thing of the past. If the neutral ever breaks connection, you will apply 240 volts across the 120 volt load, and destroy the appliances.

I need to better explain:

Using a regular 2 pole breaker from the sub panel I want to run 12-3 wire to the bathtub. I would then use 2 separate GFI receptacles. One for the pump and the other for the heater. That is why I would use a 2 gang box.

Thanks tkrussel for your help

Yes that will work, although, like I said , shared neutrals can pose a problem if the neutral is broken at any place and anytime. If you were to hire me, I would be installing two 2 wire cables to feed the GFI receptacles.

Might also consider using faceless GFI's on the wall as opposed to having them below. I do realize, however, that this may add extra work in an "old work" environment.