North Dakota is not a “tax free” state. It also taxes some Social Security benefits as well as all IRA, 401k etc distributions plus pension income.
Yet, the amount of income tax you’ll pay to the state is minimal because the brackets are very low. If you’re married you’ll pay all of 1.1% on Gross Income up to $90k. Of that amount, that which is from Social Security will be taxed even more favorably, similar to how the Feds tax it.
So essentially, you’re going to pay a couple hundred bucks in income taxes in North Dakota unless you’re making huge income.
Sales tax is middling. When state and local sales tax is accounted for, North Dakota is smack in the middle of the nation for taxable burden.
Property tax is in the middle of all states too, at 1%. Given the median value of homes in North Dakota is $155k, the actual dollar amount you pay in tax will be on the lower end.
All in all, you’ll pay some tax in retirement to live in North Dakota, but it won’t be oppressive.