Car Loan Interest Deduction Calculator

Calculates the 2025-2028 federal deduction for car loan interest created by the One Big Beautiful Bill Act (P.L. 119-21, IRC 163(h)(4)) the way IRS Schedule 1-A Part IV does: up to $10,000 of qualified passenger vehicle loan interest, then $200 off for each $1,000 or part of $1,000 of MAGI over $100,000 ($200,000 married filing jointly), so it reaches $0 at $149,001 ($249,001 joint). Checks the eligibility tests: loan originated after Dec 31 2024, new vehicle, final assembly in the US, personal use, car/minivan/van/SUV/pickup/motorcycle under 14,000 lb GVWR, first lien, not a lease. Available whether or not you itemize. Rules copied from the 2025 Schedule 1-A, Form 1040 instructions and IRS Notice 2025-57.

{
  "type": "object",
  "properties": {
    "filing_status": {
      "type": "string",
      "enum": [
        "single",
        "married_filing_jointly",
        "married_filing_separately",
        "head_of_household",
        "qualifying_surviving_spouse"
      ],
      "description": "Federal filing status."
    },
    "magi": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Modified adjusted gross income in USD (Form 1040 line 11b plus excluded foreign and Puerto Rico income)."
    },
    "tax_year": {
      "type": "integer",
      "minimum": 2025,
      "maximum": 2028,
      "description": "Tax year, 2025 to 2028. The deduction ends after 2028."
    },
    "interest_paid": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Interest paid or accrued on the vehicle loan in the year, in USD (the lender's year-end statement)."
    },
    "interest_deducted_elsewhere": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Part of that interest already deducted on Schedule C, E or F. It cannot be deducted twice."
    },
    "loan_origination_date": {
      "type": "string",
      "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
      "description": "Date the loan was originated, YYYY-MM-DD. Must be after 2024-12-31."
    },
    "new_vehicle": {
      "type": "boolean",
      "description": "True if the original use starts with you (new). Used vehicles do not qualify."
    },
    "us_final_assembly": {
      "type": "boolean",
      "description": "True if final assembly was in the United States (vehicle label or NHTSA VIN decoder)."
    },
    "personal_use": {
      "type": "boolean",
      "description": "True if you expect personal use more than 50% of the time."
    },
    "vehicle_type": {
      "type": "string",
      "enum": [
        "car",
        "minivan",
        "van",
        "suv",
        "pickup",
        "motorcycle",
        "other"
      ],
      "description": "car, minivan, van, suv, pickup, motorcycle or other."
    },
    "gvwr_under_14000_lbs": {
      "type": "boolean",
      "description": "True if the gross vehicle weight rating is under 14,000 pounds."
    },
    "secured_by_first_lien": {
      "type": "boolean",
      "description": "True if the loan is secured by a first lien on the vehicle."
    },
    "is_lease": {
      "type": "boolean",
      "description": "True if this is a lease. Lease payments never qualify."
    },
    "marginal_tax_rate": {
      "type": "number",
      "minimum": 0,
      "maximum": 0.37,
      "description": "Your federal marginal rate as a decimal (e.g. 0.22) to estimate the tax saved."
    }
  },
  "required": [
    "filing_status",
    "magi",
    "tax_year",
    "interest_paid"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}

Calculates the deductible state and local tax (SALT) on Schedule A under the One Big Beautiful Bill Act cap (IRC 164(b)(6)-(7)): $40,000 for 2025 and $40,400 for 2026 ($20,000 / $20,200 married filing separately), rising 1% a year through 2029, reduced by 30% of MAGI over $500,000 (2025) or $505,000 (2026) but never below $10,000, then back to a flat $10,000 in 2030. Uses the IRS State and Local Tax Deduction Worksheet. Optionally compares itemizing with the standard deduction. Amounts copied from the 2025 Schedule A instructions, the 2026 draft Schedule A and the statute.

{
  "type": "object",
  "properties": {
    "filing_status": {
      "type": "string",
      "enum": [
        "single",
        "married_filing_jointly",
        "married_filing_separately",
        "head_of_household",
        "qualifying_surviving_spouse"
      ],
      "description": "Federal filing status."
    },
    "magi": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Modified adjusted gross income in USD (Form 1040 line 11b plus excluded foreign and Puerto Rico income)."
    },
    "tax_year": {
      "type": "integer",
      "minimum": 2025,
      "maximum": 2035,
      "description": "Tax year, 2025 or later. 2027-2029 amounts are the statutory 101% steps; 2030 on is $10,000."
    },
    "state_and_local_taxes": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "State and local income (or sales) tax plus real estate and personal property tax paid in the year (Schedule A line 5d)."
    },
    "other_itemized_deductions": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Other itemized deductions (mortgage interest, gifts to charity, medical over the floor). Give it to compare itemizing with the standard deduction."
    }
  },
  "required": [
    "filing_status",
    "magi",
    "tax_year",
    "state_and_local_taxes"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}

Returns the official 2025 and 2026 federal income tax brackets and standard deductions after the One Big Beautiful Bill Act: 2026 standard deduction $16,100 single, $32,200 joint, $24,150 head of household (Rev. Proc. 2025-32), 2025 $15,750 / $31,500 / $23,625, plus the additional amount for age 65 or blind. Optionally computes the tax and marginal rate on a taxable income. Says plainly that 2027 amounts are not yet published (checked against the Internal Revenue Bulletin and irs-drop on 2026-11-02).

{
  "type": "object",
  "properties": {
    "tax_year": {
      "type": "integer",
      "minimum": 2025,
      "maximum": 2027,
      "description": "2025 or 2026. 2027 returns a not-yet-published error."
    },
    "filing_status": {
      "type": "string",
      "enum": [
        "single",
        "married_filing_jointly",
        "married_filing_separately",
        "head_of_household",
        "qualifying_surviving_spouse"
      ],
      "description": "Leave out to get all filing statuses."
    },
    "taxable_income": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Taxable income to compute tax on (needs filing_status)."
    }
  },
  "required": [
    "tax_year"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}

Calculates the child tax credit as Schedule 8812 does after the One Big Beautiful Bill Act: $2,200 per qualifying child under 17 for 2025 and 2026, $500 per other dependent, reduced by 5% of MAGI over $400,000 joint / $200,000 others (excess rounded up to the next $1,000), limited by tax liability, with the refundable additional child tax credit of up to $1,700 per child at 15% of earned income over $2,500. Amounts from the 2025 Schedule 8812 and Rev. Proc. 2025-32.

{
  "type": "object",
  "properties": {
    "filing_status": {
      "type": "string",
      "enum": [
        "single",
        "married_filing_jointly",
        "married_filing_separately",
        "head_of_household",
        "qualifying_surviving_spouse"
      ],
      "description": "Federal filing status."
    },
    "magi": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Modified adjusted gross income in USD (Form 1040 line 11b plus excluded foreign and Puerto Rico income)."
    },
    "tax_year": {
      "type": "integer",
      "minimum": 2025,
      "maximum": 2027,
      "description": "2025 or 2026. 2027 is not yet published."
    },
    "qualifying_children": {
      "type": "integer",
      "minimum": 0,
      "maximum": 20,
      "description": "Children under 17 at year end with a valid SSN."
    },
    "other_dependents": {
      "type": "integer",
      "minimum": 0,
      "maximum": 20,
      "description": "Other dependents (credit for other dependents, $500 each)."
    },
    "earned_income": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Earned income for the refundable part. Defaults to MAGI."
    },
    "tax_liability_before_credits": {
      "type": "number",
      "minimum": 0,
      "maximum": 10000000000,
      "description": "Income tax before credits (Form 1040 line 18). Estimated from MAGI if left out."
    }
  },
  "required": [
    "filing_status",
    "magi",
    "tax_year",
    "qualifying_children"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}