 Income tax 2023-2024, self-employed, what you need to know. Get ready and some coffee, because if you try telling an IRS auditor a joke about taxes, they won't depreciate it. Most of this information comes from Publication 334, Tax Guide for Small Business for Individuals who use Schedule C, Tax Year 2023, which you can find on the IRS website at irs.gov, irs.gov. Looking at the individual income tax formula, mirroring the calculation on the Form 1040, remembering the first half of the income tax formula is in essence an income statement. Income statements typically having income minus expenses resulting in net income, here having income minus various deductions resulting in taxable income with business income.