None.
When a person dies, they can pass up to $5.1M dollars in assets to their heirs with no tax reporting required. The assets are inherited by the legal beneficiaries "tax free" basically.
When you give a gift to any one person in excess of $14K in any one tax year, then the amount or value of that gift goes against your $5.1M. You are required to report it to the IRS. No taxes will be assessed. It just counts against the $5.1M that can be passed taxed free to your heirs when you pass away.