South Dakota has no income tax. Thus ANY income is not taxed.
South Dakota also has a moderately low sales tax too, clocking in at around 6.40%.
Property taxes are on the high end, around 1.21%. Not extraordinarily high but in the top 20 nationwide.
However, South Dakota median property isn’t overly expensive so the actual dollars residents pay in property tax are in the bottom half of the country.
All in all, no income tax, low sales tax, middling property tax, South Dakota is very favorable for retirees.