@Hailun Feng , my personal preference would be to ask for a new EIN for the C-corp. I say this because (a) it is clean cut change to a new entity; (b) a C-Corp has a different type of account/ accounting than an LLC; (c) generally you have to choose the reporting entity class by the first filing --- this is because a C-Corp is very different from a dis-regarded entity -- it stands on its own. ( even if the DBA and type of business is the same . Also your creditors will have different recourse than as a dis-regarded entity.
Also note while you can prepare your dis-regarded entity with Individual TurboTax, you will need TurboTax Business to do the one for your C-Corp.
That's my view based on my own experience with dis-regarded entity and C-Corp.
Is there more I can do for you.
