There is no tax on assets that go through Probate, however there is an Inheritance tax on assets that transfer as a result of someone passing away, regardless if they are Probate or Non-Probate assets. The rates are broken into 4 groups based on to whom the asset is going.
1. The Spousal Rate (includes spouses and charities) is 0%.
2. The Lineal Rate (includes children, grandchildren, great-grandchildren... and parents, grandparents, great-grandparent...) is 4.5%
3. The Sibling Rate (includes the decedent's siblings) is 12%
4. The Collateral Rate (everyone else in the world) is 15%