Your tax obligation to California depends on whether you are a paid employee (your earnings are reported to you on a W-2), or an independent contractor (your earnings are reported to you on a 1099-NEC).
CA taxes non-residents only on CA-source income. If you are a W-2 employee, and you never physically work within CA, then your work earnings are not CA-source and are not taxed by CA.
However, if you are an independent contractor, then any income you receive from clients based in California is considered CA-source income, and is taxable by CA.
This is an income tax forum, and questions about SD's unemployment laws are beyond its scope.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
