The federal part applies everywhere
Wherever you live, self-employment income carries two federal taxes. The first is self-employment tax at 15.3% of net earnings, covering Social Security and Medicare — the portions an employer would normally split with you. The second is federal income tax, calculated on your profit after the standard deduction and the deductible half of your self-employment tax.
This part does not change based on your state. A freelancer in South Dakota and a freelancer anywhere else owe the same federal self-employment tax on the same profit. The self-employment tax calculator works out that figure.
What South Dakota adds
Nothing, on income. With no individual income tax, South Dakota does not tax your freelance profit at the state level, so the federal figure above is your whole income tax picture. States without an income tax typically raise revenue in other ways — sales tax, property tax, or business-level taxes — so the saving is real but not always as large as the headline suggests once other costs are counted.
South Dakota levies no individual income tax and no corporate income tax.
Quarterly payments in South Dakota
Because South Dakota has no individual income tax, your quarterly estimated payments go to the IRS only. There is no parallel state estimated payment on your freelance income, which removes a whole layer of paperwork that freelancers in most other states deal with.
The quarterly estimated tax calculator handles the federal side, and the deadlines guide lists the federal due dates.
Deductions work the same way
Business expenses reduce your net profit, which lowers your federal self-employment tax and federal income tax. Software, equipment, a home office, mileage, and professional fees commonly qualify. The write-off guide covers what usually counts.