Annual limit
Combined IRA contribution limit (traditional + Roth) is set yearly. Catch-up contributions for those age 50+ add a fixed dollar amount. Contributions must come from earned income — wages, self-employment, or alimony from a pre-2019 divorce.
Deductibility
If neither you nor your spouse is covered by an employer retirement plan, the full contribution is deductible at any income level. If covered, the deduction phases out between income thresholds dependent on filing status and whose plan covers whom.
Nondeductible contributions
Above the deductibility phase-out, you may still contribute but the contribution is nondeductible. File Form 8606 to track the basis. Backdoor Roth strategies depend on properly tracking nondeductible basis through Form 8606.
Deadline
Contributions for a tax year may be made up to the original (not extended) return due date — generally April 15 of the following year. Designate the contribution year explicitly when funding to avoid having it counted toward the wrong year.
Spousal IRA
A working spouse can fund an IRA for a non-working spouse. The combined contribution limit is doubled, but the contributions must come from the working spouse's earned income.
Where this fits in the larger Schedule C picture
Schedule C has more than two dozen named expense lines plus an "Other expenses" catch-all. For most small businesses, four or five lines drive the bulk of the deduction total — vehicle, home office, depreciation, contract labor or wages, and supplies — and the remaining lines individually contribute small amounts that nevertheless add up. Treating each named line as a recurring decision rather than an afterthought, and revisiting the categories each January, often surfaces $2,000–$5,000 in additional legitimate deductions that a less disciplined process would have missed entirely.
Documentation that survives an exam
An IRS examination of this deduction will request three things: proof of payment (bank or card statement), proof of the underlying transaction (invoice or receipt), and proof of business purpose (a contemporaneous note or calendar entry). The first two are usually trivial to produce; the third is where most filers fall short. Capturing business purpose at the moment of the expense — a one-line note in your bookkeeping software or a category and memo on the receipt-capture app — converts a generic charge into a documented deduction that will withstand scrutiny three to six years later when memory has faded.