United States tax deadlines 2026.

Illinois Individual Income Tax Return (Form IL-1040) for sole proprietors and single-member LLCs. Covers the flat 4.95% rate, Illinois base income computation from federal AGI, Schedule M addition and subtraction modifications, property tax credit (Schedule ICR), earned income credit, and the full return assembly. Primary source: 35 ILCS 5/.

Illinois Estimated Income Tax (Form IL-1040-ES) for self-employed individuals. Covers quarterly payment requirements, 4.95% flat rate computation, safe harbour rules, underpayment penalty calculation, and payment schedule. Primary source: 35 ILCS 5/803; 86 Ill. Admin. Code 100.8010.

Use this skill whenever asked about states with no sales tax, Alaska local sales tax, Delaware gross receipts tax, Montana resort tax, New Hampshire meals and rooms tax, Oregon Corporate Activity Tax, or tax obligations in AK, DE, MT, NH, or OR. Trigger on phrases like "no sales tax states", "Alaska sales tax", "Delaware gross receipts", "Montana resort tax", "New Hampshire meals tax", "Oregon CAT", "Oregon no sales tax", or any request involving tax compliance in states that do not impose a general statewide sales tax. ALWAYS load us-sales-tax first for federal context.

Illinois Sales Tax return (Form ST-1) for self-employed individuals. Covers all four Illinois occupation and use taxes (ROT, UT, SOT, SUT), state and local rates, origin-based sourcing, vendor discount, and filing frequencies. Primary source: 35 ILCS 120/ (ROT), 35 ILCS 105/ (UT), 35 ILCS 115/ (SOT), 35 ILCS 110/ (SUT).

Tier 2 content skill for computing the self-employed retirement contribution deduction for US sole proprietors and single-member LLCs disregarded for federal tax purposes. Covers tax year 2025 SEP-IRA, Solo 401(k), SIMPLE IRA, and traditional/Roth IRA options with SECURE 2.0 super catch-up provisions. Handles the net SE earnings calculation, the 92.35% adjustment, the employer contribution formula (20% effective rate for sole props), employee deferral limits ($23,500), catch-up and super catch-up contributions, the SEP-IRA 25% limit ($70,000 cap), SIMPLE IRA rules, traditional and Roth IRA income limits and deductibility phase-outs, and establishment/contribution deadlines. Consumes Schedule C net profit and SE tax from us-schedule-c-and-se-computation. Feeds QBI computation in us-qbi-deduction. MUST be loaded alongside us-tax-workflow-base v0.1 or later. Federal only. No state tax.

Tier 2 content skill for computing the self-employed health insurance deduction under IRC §162(l) for US sole proprietors and single-member LLCs disregarded for federal tax purposes. Covers tax year 2025 rules including the 100% deduction for medical, dental, vision, and qualified long-term care premiums, the age-based long-term care premium limits, the net SE earnings limitation, the employer-sponsored plan eligibility bar, the Medicare premium eligibility rules (Parts A voluntary, B, D, Medigap), COBRA continuation premiums, ACA Marketplace interaction with the Premium Tax Credit, the month-by-month coverage calculation, and the Schedule 1 Line 17 reporting position. Consumes Schedule C net profit and SE tax from us-schedule-c-and-se-computation. Feeds QBI computation in us-qbi-deduction. MUST be loaded alongside us-tax-workflow-base v0.1 or later. Federal only. No state tax.

Tier 2 content skill for computing Schedule C bottom line, Form 8829 home office (actual method), and Schedule SE self-employment tax for US sole proprietors and single-member LLCs disregarded for federal tax. Covers tax year 2025 with the 2025 Social Security wage base of $176,100, the 92.35% net SE earnings adjustment under IRC 1402(a)(12), the 12.4% OASDI rate, the 2.9% Medicare rate, and the 0.9% Additional Medicare Tax thresholds. Handles Schedule C Lines 1-32, the 280A home office gross income limitation and carryover, Form 8829 indirect expense allocation, the 1402 net SE earnings computation, the optional methods under 1402(a)(15) and 1402(l), the deductible half of SE tax under 164(f), and the at-risk indicators on Line 32. Consumes classified transactions from us-sole-prop-bookkeeping. Defers QBI, retirement, SE health insurance, and quarterly estimated tax to companion skills. MUST be loaded alongside us-tax-workflow-base v0.1+. Federal only. ALWAYS read this skill before computing Schedule C, SE tax, or home office deductions.

Tier 2 content skill for determining which contractor payments made by a US sole proprietor or single-member LLC require issuing Form 1099-NEC and producing the information returns for tax year 2025. Covers the §6041A $600 reporting threshold (rising to $600 for electronic payments after repeated deferrals of the §6050W $600 threshold), the corporate exception under Treas. Reg. §1.6041-3(p), the attorney exception under §6045(f), the medical/health care exception under §6041A(a)(2), the Form W-9 collection requirement, backup withholding at 24% under §3406, the January 31 filing deadline under §6071(c), e-filing requirements under §6011(e) and the 2025 threshold of 10 forms, penalties for failure to file under §6721 and failure to furnish under §6722, TIN matching and B-notice procedures, and state filing requirements. MUST be loaded alongside us-tax-workflow-base v0.1+. Federal only.