WI Income Tax

Tax brackets — Single / Head of Household

| Taxable income bracket | Marginal rate | |------------------------|---------------| | $0 – $14,680 | 3.50% | | $14,681 – $50,480 | 4.40% | | $50,481 – $323,290 | 5.30% | | $323,291 and above | 7.65% |

Tax brackets — Married filing jointly

| Taxable income bracket | Marginal rate | |------------------------|---------------| | $0 – $19,580 | 3.50% | | $19,581 – $67,300 | 4.40% | | $67,301 – $431,060 | 5.30% | | $431,061 and above | 7.65% |

Tax brackets — Married filing separately

| Taxable income bracket | Marginal rate | |------------------------|---------------| | $0 – $9,790 | 3.50% | | $9,791 – $33,650 | 4.40% | | $33,651 – $215,530 | 5.30% | | $215,531 and above | 7.65% |

Standard deduction (sliding scale)

| Filing status | Maximum amount | Phase-out begins at WI AGI | |---------------|---------------|---------------------------| | Single | $14,260 | Phases out as income rises | | Married filing jointly | $26,510 | Phases out as income rises | | Married filing separately | $12,630 | Phases out as income rises | | Head of household | $18,220 | Phases out as income rises |

Personal exemptions table

| Item | Amount | |------|--------| | Personal exemption — taxpayer | $700 | | Personal exemption — spouse (MFJ) | $700 | | Each dependent | $700 | | Additional — age 65+ | $250 per person |

Other key thresholds table

| Item | Amount | Source | |------|--------|--------| | Filing deadline | April 15 | Wis. Stat. §71.03(8) | | Extension | October 15 (automatic with federal) | Wis. Stat. §71.03(8)(b) | | Estimated tax threshold | $500 expected liability | Wis. Stat. §71.09 | | State sales tax rate | 5% | Wis. Stat. §77.52 | | County sales tax | 0.5% (most counties) | Wis. Stat. §77.70 |

Self-employment tax deduction flow-through

The federal deduction for 50% of self-employment tax reduces federal AGI → flows through to Wisconsin automatically.

Retirement contributions flow-through

SEP-IRA, SIMPLE IRA, solo 401(k) contributions reduce federal AGI → flow through automatically.

Health insurance deduction flow-through

Self-employed health insurance deduction reduces federal AGI → flows through automatically.

QBI deduction not conformed

Wisconsin does NOT conform to the QBI deduction. Since Wisconsin starts from AGI (before QBI), the §199A deduction is not part of Wisconsin's computation. Wisconsin taxable income will be higher by the QBI amount.

Home office deduction flow-through

Reduces Schedule C net profit → reduces federal AGI → flows through.

Retirement income subtraction

For 2025+, taxpayers age 67+ may subtract up to $24,000 of qualifying retirement income (Act 15). Not typically relevant for active self-employed, but may apply to semi-retired sole proprietors.Act 15

Estimated tax payments requirement

Required if expected Wisconsin tax after withholding and credits exceeds $500. Due dates: April 15, June 15, September 15, January 15. Form 1-ES (voucher).

[T1-WI-1] Tax computation

Apply the graduated rate schedule to Wisconsin taxable income based on filing status. Use Wisconsin tax tables (for taxable income under $100,000) or rate schedules (for $100,000+).T1-WI-1

[T1-WI-2] Starting point

Begin with federal adjusted gross income from Form 1040, Line 11. Enter on Wisconsin Form 1, Line 1.T1-WI-2

[T1-WI-3] Wisconsin additions (Schedule AD)

Common additions for self-employed: - State/local income tax refund (if deducted federally in prior year) - Wisconsin does not conform to federal bonus depreciation §168(k) — add back the difference between federal and Wisconsin depreciation (Section 179 is generally allowed) - Certain capital gain exclusions claimed federally but not recognized by WIT1-WI-3

[T1-WI-4] Wisconsin subtractions (Schedule SB)

Common subtractions: - Interest from US government obligations (Treasury bonds) - Retirement income subtraction (age 67+, up to $24,000 per Act 15) - Net operating loss differences (Wisconsin has its own NOL rules) - College savings account (EdVest/Tomorrow's Scholar) contributions — up to $5,130 per beneficiaryT1-WI-4

[T1-WI-5] Standard deduction computation

Wisconsin uses a sliding-scale standard deduction that decreases as income rises. The deduction amount is calculated using tables in the Form 1 instructions. High-income self-employed individuals may receive $0 standard deduction.T1-WI-5

[T1-WI-6] Filing due date

April 15 following the tax year (April 15, 2026 for TY 2025). Extension: October 15 (automatic if federal extension is obtained; file Form 1 by October 15 but pay by April 15).T1-WI-6

[T1-WI-7] Estimated tax payments

Required if expected liability exceeds $500. Due dates: April 15, June 15, September 15, January 15. Use Form 1-ES. Underpayment penalty applies if <90% of current year or <100% of prior year liability paid timely.T1-WI-7

[T1-WI-8] Wisconsin Earned Income Credit

Varies by number of children: - 1 qualifying child: 4% of federal EIC - 2 qualifying children: 11% of federal EIC - 3+ qualifying children: 34% of federal EIC - No children: not eligible for WI EIC Partially refundable.T1-WI-8

[T2-WI-1] Residency determination

Wisconsin defines a resident as a person domiciled in Wisconsin. Domicile is determined by intent and ties (voter registration, driver's license, home ownership, family location). A non-domiciliary maintaining an abode in WI and present 183+ days may also be treated as a resident.T2-WI-1

[T2-WI-2] Depreciation differences

Wisconsin requires its own depreciation schedule for assets placed in service after 2000 where federal bonus depreciation was claimed. This creates a tracking requirement — Wisconsin depreciation may differ from federal depreciation in each year. Reviewer must maintain a Wisconsin-specific depreciation schedule.T2-WI-2

[T2-WI-3] Multi-state credit

Wisconsin allows a credit for net income taxes paid to other states on income also taxable by Wisconsin. The credit cannot exceed Wisconsin tax attributable to the other-state income. Computed on Schedule OS.T2-WI-3

[T2-WI-4] Sliding-scale standard deduction phase-out

The exact amount depends on the taxpayer's Wisconsin AGI and filing status. For higher-income self-employed individuals, the standard deduction may be $0, making this determination critical. The phase-out formula changes annually.T2-WI-4

[T2-WI-5] Manufacturer's and agriculture credit

Certain qualifying manufacturing or agricultural activities may be eligible for a credit that can reduce the effective tax rate. Requires detailed analysis of qualifying income.T2-WI-5

Supplier pattern library table

| Income/deduction type | Wisconsin treatment | Notes | |----------------------|---------------------|-------| | Schedule C net profit | Included via federal AGI | No adjustment | | Self-employment tax deduction | Included via federal AGI reduction | No adjustment | | SEP/SIMPLE/solo 401(k) | Included via federal AGI reduction | No adjustment | | QBI deduction (§199A) | NOT included — WI starts from AGI | WI taxable income higher | | Self-employed health insurance | Included via federal AGI reduction | No adjustment | | Home office deduction | Included via Schedule C → AGI reduction | No adjustment | | Federal bonus depreciation (§168(k)) | Add back; use WI depreciation | Tracking required | | US government bond interest | Subtract | Exempt from WI tax | | State/local tax refund | Add if deducted in prior year | Follows federal treatment | | Social Security benefits | Exempt (not included in WI income) | Subtract if included in AGI |

Form mapping table

| Form 1 Line | Description | Source | |-------------|-------------|--------| | Line 1 | Federal adjusted gross income | Form 1040, Line 11 | | Line 2 | Wisconsin additions (Schedule AD) | Computed | | Line 3 | Total (Line 1 + Line 2) | Computed | | Line 4 | Wisconsin subtractions (Schedule SB) | Computed | | Line 5 | Wisconsin income (Line 3 − Line 4) | Computed | | Line 7 | Standard deduction (sliding scale) | From instructions table | | Line 9 | Exemptions ($700 × number) | Computed | | Line 11 | Wisconsin taxable income | Line 5 − 7 − 9 | | Line 12 | Tax (from tax table or rate schedule) | Per brackets | | Line 19 | Credits | Various | | Line 26+ | Payments (withholding, estimated) | W-2s, Form 1-ES |

Refusal catalogue table

| ID | Refusal | Reason | |----|---------|--------| | R-WI-1 | Part-year resident return | Requires income allocation | | R-WI-2 | Nonresident return (Form 1NPR) | Different form and sourcing rules | | R-WI-3 | Wisconsin corporate income/franchise tax | Different tax type (Form 4) | | R-WI-4 | Wisconsin estate/inheritance tax | No longer in effect (repealed) | | R-WI-5 | Manufacturer's/agriculture credit computation | Specialized credit with complex qualification | | R-WI-6 | Amended returns (Form 1X) | Requires additional procedures | | R-WI-7 | Wisconsin alternative minimum tax (Schedule MT) | Requires separate parallel computation | | R-WI-8 | Farmland preservation credit | Specialized credit requiring assessments |

R-WI-1

Part-year resident returnRequires income allocation

R-WI-2

Nonresident return (Form 1NPR)Different form and sourcing rules

R-WI-3

Wisconsin corporate income/franchise taxDifferent tax type (Form 4)

R-WI-4

Wisconsin estate/inheritance taxNo longer in effect (repealed)

R-WI-5

Manufacturer's/agriculture credit computationSpecialized credit with complex qualification

R-WI-6

Amended returns (Form 1X)Requires additional procedures

R-WI-7

Wisconsin alternative minimum tax (Schedule MT)Requires separate parallel computation

R-WI-8

Farmland preservation creditSpecialized credit requiring assessments