26 U.S.C. § 6017 — Self-employment tax returns

Every individual, except a "nonresident alien individual" (a term this section does not define), who has "net earnings from self-employment" (a term this section does not define) of $400 or more for the "taxable year^*" (a term this section does not define) must make a return for the self-employment tax imposed by chapter 2. If a husband and wife file a "joint return^*" under section 6013, the tax imposed by chapter 2 must not be calculated on their income together. Instead, it must be the sum of the tax calculated under chapter 2 on each spouse’s separate "self-employment income" (a term this section does not define).