Use this skill whenever asked about Colorado individual income tax for self-employed individuals or sole proprietors — filing Form DR 0104, CO estimated tax (Form DR 0104EP), Colorado flat tax rate, Colorado additions and subtractions, or any query involving Colorado state income tax compliance. Trigger on phrases like "Colorado income tax", "CO income tax", "Form 104", "DR 0104", "Colorado estimated tax", "Colorado self-employed tax", "TABOR refund", or "C.R.S. §39-22".
Source-cited draft.Written from sources but not reviewed by a licensed practitioner, so it may be incomplete or wrong. General reference only; don't file or take a position on it without professional review.
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Metadata table
| Field | Value | |---|---| | Jurisdiction | Colorado, United States | | Jurisdiction code | US-CO | | Tax authority | Colorado Department of Revenue | | Filing portal | https://revenueonline.colorado.gov | | Legislation citation | C.R.S. §39-22 (Income Tax) | | Primary form | DR 0104 — Colorado Individual Income Tax Return | | Filing deadline | April 15 (follows federal deadline) | | Version | 0.1 | | Generated | 2026-05-22 | | Validation status | AI-drafted — Q3 |
All statuses
4.4%All Colorado taxable income
Tax rate table (TY 2025)
| Filing status | Rate | Applies to | |---|---|---| | All statuses | 4.4% | All Colorado taxable income |
Married Filing Separately
$15,000
Married Filing Jointly
$30,000
Married Filing Separately
$15,000
Head of Household
$22,500
Standard deduction table (TY 2025)
| Filing status | Standard deduction | |---|---| | Single | $15,750 | | Married Filing Jointly | $31,500 | | Married Filing Separately | $15,750 | | Head of Household | $23,625 |
Starting point
Colorado begins with federal taxable income (federal Form 1040, Line 15). This is unusual — most states start from federal AGI.Federal Form 1040, Line 15
Scope. This skill covers Colorado individual income tax for self-employed individuals and sole proprietors filing Form DR 0104. It addresses tax computation, deductions, estimated payments, and form mapping. Quality tier. Q3 — AI-drafted with citations; not independently verified by a licensed professional.
Metadata table
| Field | Value |
|---|---|
| Jurisdiction | Colorado, United States |
| Jurisdiction code | US-CO |
| Tax authority | Colorado Department of Revenue |
| Filing portal | https://revenueonline.colorado.gov |
| Legislation citation | C.R.S. §39-22 (Income Tax) |
| Primary form | DR 0104 — Colorado Individual Income Tax Return |
| Filing deadline | April 15 (follows federal deadline) |
| Version | 0.1 |
| Generated | 2026-05-22 |
| Validation status | AI-drafted — Q3 |
Tax rate table (TY 2025)
| Filing status | Rate | Applies to |
|---|---|---|
| All statuses | 4.4% | All Colorado taxable income |
Colorado imposes a flat income tax rate of 4.4% on all Colorado taxable income, regardless of filing status or income level. The rate was reduced from 4.55% (TY 2024) to 4.4% (TY 2025) through TABOR-related adjustments.
Standard deduction table (TY 2025)
| Filing status | Standard deduction |
|---|---|
| Single | $15,000 |
| Married Filing Jointly | $30,000 |
| Married Filing Separately | $15,000 |
| Head of Household | $22,500 |
Colorado uses the federal standard deduction amounts. For TY 2025: (These are the federal amounts; Colorado taxable income starts from federal taxable income, which already incorporates the federal standard deduction or itemized deductions.)
Colorado's Taxpayer's Bill of Rights (TABOR) limits state revenue growth. When revenue exceeds limits, taxpayers receive refunds. These refunds are typically claimed on the DR 0104 or issued automatically.
Key implication: Because Colorado starts from federal taxable income, the federal standard deduction (or itemized deductions) is already incorporated. Taxpayers cannot separately choose between standard/itemized for Colorado — they must use whatever they chose federally.
Tier 1 rules table
| # | Rule | Logic |
|---|---|---|
| T1-01 | Apply 4.4% flat rate to Colorado taxable income | Single rate × taxable income |
| T1-02 | Start from federal taxable income | Federal Form 1040, Line 15 |
| T1-03 | Social Security subtraction (age 55–64) | Partial subtraction available |
| T1-04 | Social Security subtraction (age 65+) | Full subtraction of benefits included in federal taxable income |
| T1-05 | Estimated tax threshold | Net tax after withholding/credits > $1,000 |
| T1-06 | U.S. government interest subtraction | Subtract interest on U.S. obligations included in federal taxable income |
| T1-07 | State refund addition | Add back state tax refund if itemized in prior year |
Tier 2 rules table
| # | Rule | Why judgment needed |
|---|---|---|
| T2-01 | Colorado-source capital gains subtraction | Must meet holding period and Colorado-source requirements |
| T2-02 | Part-year resident apportionment | Requires Form DR 0104PN and income allocation |
| T2-03 | TABOR refund election | Taxpayer may choose between cash refund or credit against future tax |
| T2-04 | Charitable contribution subtraction | Colorado allows additional subtraction for certain charitable giving (above federal benefit) |
| T2-05 | Multistate income apportionment | Business income from multiple states requires analysis |
| T2-06 | Net operating loss | Colorado follows federal NOL rules with some modifications |
Supplier pattern library table
| Pattern on bank/CC statement | Likely meaning |
|---|---|
CO DEPT OF REVENUE / COLORADO DOR | Colorado income tax payment |
REVENUE ONLINE CO | Payment via Revenue Online portal |
STATE OF CO TAX | State tax payment |
COLORADO DEPT REV | Department of Revenue payment |
CO DR 0104EP | Estimated tax payment |
CO DEPT OF REVENUE / COLORADO DOR — Colorado income tax paymentREVENUE ONLINE CO — Payment via Revenue Online portalSTATE OF CO TAX — State tax paymentCOLORADO DEPT REV — Department of Revenue paymentCO DR 0104EP — Estimated tax paymentForm mapping table
| Computed value | Form DR 0104 line |
|---|---|
| Federal taxable income | Line 1 |
| Colorado additions | Line 3 (from DR 0104AD) |
| Colorado subtractions | Line 5 (from DR 0104AD) |
| Colorado taxable income | Line 12 |
| Colorado tax (4.4% × Line 12) | Line 13 |
| Alternative minimum tax | Line 14 |
| Credits (DR 0104CR) | Line 18 |
| Net tax | Line 20 |
| Estimated payments | Line 30 |
| Balance due / refund | Lines 36–37 |
This skill must refuse and recommend professional review when:
Refusal catalogue table
| # | Condition |
|---|---|
| R-01 | Taxpayer has multistate business activity requiring apportionment |
| R-02 | Taxpayer is a part-year resident with complex sourcing (DR 0104PN) |
| R-03 | Taxpayer has Colorado NOL carryforward with state-specific modifications |
| R-04 | Questions about Colorado enterprise zone credits |
| R-05 | Issues involving Colorado alternative minimum tax |
| R-06 | TABOR refund mechanism questions requiring legal interpretation |
| R-07 | Colorado child care / earned income tax credit calculations |
| R-08 | Audit representation or controversy matters |
| R-09 | Any question about tax fraud, evasion, or aggressive positions |
This skill and its outputs are provided for informational and computational purposes only and do not constitute tax, legal, or financial advice. Open Accountants and its contributors accept no liability for any errors, omissions, or outcomes arising from the use of this skill. All outputs must be reviewed and signed off by a qualified professional (such as a CPA, EA, tax attorney, or equivalent licensed practitioner in your jurisdiction) before filing or acting upon.
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Other Colorado computations in the OpenAccountants Tax Library.
Colorado additions (DR 0104AD)
Add back amounts deducted federally but not recognized by Colorado (e.g., state income tax refund if previously deducted, certain bond interest from other states).DR 0104AD
Colorado subtractions (DR 0104AD)
Subtract Colorado-exempt income (e.g., Social Security benefits for age 55+, PERA/DPS pension income, U.S. government interest, Colorado-source capital gains subtraction).DR 0104AD
Colorado tax result
Colorado taxable income × 4.4% = Colorado tax.
Federal conformity rules
Colorado is a strong conformity state — it starts from federal taxable income, so nearly all federal provisions automatically flow through. Schedule C business deductions, above-the-line deductions, and the QBI deduction (§199A) all flow through to Colorado because they reduce federal taxable income.
QBI deduction flow-through
Fully flows through to Colorado because Colorado starts from federal taxable income (Line 15), which is calculated after the QBI deduction.§199A
SE health insurance deduction flow-through
Reduces federal AGI (above-the-line), ultimately reducing federal taxable income, which flows to Colorado.
Retirement contributions flow-through
SEP-IRA and Solo 401(k) contributions reduce federal AGI → federal taxable income → Colorado starting point.
Home office deduction flow-through
Federal home office deduction flows through Schedule C → federal AGI → federal taxable income → Colorado.
Threshold
> $1,000Form DR 0104EP
Safe harbor
Pay the lesser of 70% of current year tax or 100% of prior year tax (110% for high-income).Form DR 0104EP
Due dates
April 15, June 15, September 15, January 15.Form DR 0104EP
Payment methods
Revenue Online (revenueonline.colorado.gov), credit/debit card, e-check, EFT, or mail Form DR 0104EP with check to Colorado Department of Revenue, Denver, CO 80261-0008.Form DR 0104EP
Tier 1 rules table
| # | Rule | Logic | |---|---|---| | T1-01 | Apply 4.4% flat rate to Colorado taxable income | Single rate × taxable income | | T1-02 | Start from federal taxable income | Federal Form 1040, Line 15 | | T1-03 | Social Security subtraction (age 55–64) | Partial subtraction available | | T1-04 | Social Security subtraction (age 65+) | Full subtraction of benefits included in federal taxable income | | T1-05 | Estimated tax threshold | Net tax after withholding/credits > $1,000 | | T1-06 | U.S. government interest subtraction | Subtract interest on U.S. obligations included in federal taxable income | | T1-07 | State refund addition | Add back state tax refund if itemized in prior year |
Apply 4.4% flat rate to Colorado taxable income
T1-01Single rate × taxable income
Start from federal taxable income
T1-02Federal Form 1040, Line 15
Social Security subtraction (age 55–64)
T1-03Partial subtraction available
Social Security subtraction (age 65+)
T1-04Full subtraction of benefits included in federal taxable income
Estimated tax threshold
T1-05Net tax after withholding/credits > $1,000
U.S. government interest subtraction
T1-06Subtract interest on U.S. obligations included in federal taxable income
State refund addition
T1-07Add back state tax refund if itemized in prior year
Tier 2 rules table
| # | Rule | Why judgment needed | |---|---|---| | T2-01 | Colorado-source capital gains subtraction | Must meet holding period and Colorado-source requirements | | T2-02 | Part-year resident apportionment | Requires Form DR 0104PN and income allocation | | T2-03 | TABOR refund election | Taxpayer may choose between cash refund or credit against future tax | | T2-04 | Charitable contribution subtraction | Colorado allows additional subtraction for certain charitable giving (above federal benefit) | | T2-05 | Multistate income apportionment | Business income from multiple states requires analysis | | T2-06 | Net operating loss | Colorado follows federal NOL rules with some modifications |
Colorado-source capital gains subtraction
T2-01Must meet holding period and Colorado-source requirements
Part-year resident apportionment
T2-02Requires Form DR 0104PN and income allocation
TABOR refund election
T2-03Taxpayer may choose between cash refund or credit against future tax
Charitable contribution subtraction
T2-04Colorado allows additional subtraction for certain charitable giving (above federal benefit)
Multistate income apportionment
T2-05Business income from multiple states requires analysis
Net operating loss
T2-06Colorado follows federal NOL rules with some modifications
Supplier pattern library table
| Pattern on bank/CC statement | Likely meaning | |---|---| | `CO DEPT OF REVENUE` / `COLORADO DOR` | Colorado income tax payment | | `REVENUE ONLINE CO` | Payment via Revenue Online portal | | `STATE OF CO TAX` | State tax payment | | `COLORADO DEPT REV` | Department of Revenue payment | | `CO DR 0104EP` | Estimated tax payment |
`CO DEPT OF REVENUE` / `COLORADO DOR`
Colorado income tax payment
`REVENUE ONLINE CO`
Payment via Revenue Online portal
`STATE OF CO TAX`
State tax payment
`COLORADO DEPT REV`
Department of Revenue payment
`CO DR 0104EP`
Estimated tax payment
Form mapping table
| Computed value | Form DR 0104 line | |---|---| | Federal taxable income | Line 1 | | Colorado additions | Line 3 (from DR 0104AD) | | Colorado subtractions | Line 5 (from DR 0104AD) | | Colorado taxable income | Line 12 | | Colorado tax (4.4% × Line 12) | Line 13 | | Alternative minimum tax | Line 14 | | Credits (DR 0104CR) | Line 18 | | Net tax | Line 20 | | Estimated payments | Line 30 | | Balance due / refund | Lines 36–37 |
Federal taxable income
Line 1
Colorado additions
Line 3 (from DR 0104AD)
Colorado subtractions
Line 5 (from DR 0104AD)
Colorado taxable income
Line 12
Colorado tax (4.4% × Line 12)
Line 13
Alternative minimum tax
Line 14
Credits (DR 0104CR)
Line 18
Net tax
Line 20
Estimated payments
Line 30
Balance due / refund
Lines 36–37
Refusal catalogue table
| # | Condition | |---|---| | R-01 | Taxpayer has multistate business activity requiring apportionment | | R-02 | Taxpayer is a part-year resident with complex sourcing (DR 0104PN) | | R-03 | Taxpayer has Colorado NOL carryforward with state-specific modifications | | R-04 | Questions about Colorado enterprise zone credits | | R-05 | Issues involving Colorado alternative minimum tax | | R-06 | TABOR refund mechanism questions requiring legal interpretation | | R-07 | Colorado child care / earned income tax credit calculations | | R-08 | Audit representation or controversy matters | | R-09 | Any question about tax fraud, evasion, or aggressive positions |
R-01
Taxpayer has multistate business activity requiring apportionment
R-02
Taxpayer is a part-year resident with complex sourcing (DR 0104PN)
R-03
Taxpayer has Colorado NOL carryforward with state-specific modifications
R-04
Questions about Colorado enterprise zone credits
R-05
Issues involving Colorado alternative minimum tax
R-06
TABOR refund mechanism questions requiring legal interpretation
R-07
Colorado child care / earned income tax credit calculations
R-07
Audit representation or controversy matters
R-08
Any question about tax fraud, evasion, or aggressive positions
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