Cash inheritance is not taxable or reported, but be careful. There are many inheritances that are cash-like, but are not cash.
For example, if you inherited investments, you may owe capital gains when you sell. If the estate sells the investments for you and gives you the cash, you are still responsible for taxes on any gains unless the estate pays them (usually the estate does not pay the taxes because the tax rate on the estate is higher than on individuals). Or, if the money was in an IRA, and the estate cashed it out, and sent you the money, either you or the estate needs to pay tax on the IRA withdrawal.
But just a cash split from her bank account, that's not taxable.
