01.No state income tax, no state estate tax, no state inheritance tax.
South Dakota is one of the most tax-friendly US states for retirees on a fixed income. The only transfer tax on death is the federal estate tax (which kicks in at ~$13.99M per person in 2025). For most South Dakota families, estate planning focuses on probate avoidance and incapacity, not tax minimization. This also makes SD a popular state for dynasty trust planning by out-of-state residents, but that's a different conversation.