obbbabreaks

README

obbba-breaks

The family of tax breaks governed by the One Big Beautiful Bill Act (OBBBA, 2025) and related permanent provisions, modeled independently so caps and phase-outs never double-count:

• Child Tax Credit (§24) — $2,200/child, PERMANENT (does not sunset 2028).
• SALT cap (§164(b)(6)) — $40,400 through 2029, reverts to $10,000 in 2030.
• No-tax-on-tips deduction (§224) — $25,000 flat per return (marriage penalty), 2025-2028.
• Senior deduction (§512) — +$6,000 single / +$12,000 MFJ (both 65+), 2025-2028.
• Car-loan interest deduction (§163(h)(4)) — $10,000, NEW US-assembled vehicle, 2025-2028.

Pure, dependency-free Go math — the same engine behind the taxbreakcalc.com tax-break calculator suite.

Install

go get github.com/theluckystrike/obbba-breaks

Quick example

package main

import (
	"fmt"

	obbbabreaks "github.com/theluckystrike/obbba-breaks"
)

func main() {
	// 2 kids, single, MAGI $80k
	ctc := obbbabreaks.ChildTaxCredit(2, obbbabreaks.Single, 80_000.0)
	fmt.Println(ctc.Savings) // 4400 (dollar-for-dollar credit)

	// SALT: $50k paid in 2026 -> capped at $40,400
	salt := obbbabreaks.SALTCap(50_000.0, 2026)
	fmt.Println(salt.Deductible) // 40400

	// Tips: $30k tips, single, 22% bracket -> capped $25k
	tips := obbbabreaks.TipsDeduction(30_000.0, obbbabreaks.Single, 0.0, 0.22)
	fmt.Println(tips.Savings) // 5500 (25000 * 0.22)
}

API

Function	Description
ChildTaxCredit(children int, fs FilingStatus, magi float64) Result	§24 credit, $2,200/child, phase-out $200k/$400k.
SALTCap(stateLocalTaxPaid float64, year int) Result	§164(b)(6) itemized cap ($40,400 → $10,000 in 2030).
TipsDeduction(qualifiedTips float64, fs FilingStatus, magi, marginalRate float64) Result	§224 above-the-line deduction, $25k flat cap.
SeniorDeduction(spouses65 int, fs FilingStatus, magi, marginalRate float64) Result	§512 additional senior deduction.
CarLoanInterestDeduction(interestPaid float64, isNewVehicleUSAAssembly bool, fs FilingStatus, magi, marginalRate float64) Result	§163(h)(4) car-loan interest; gated on new US-assembled vehicle.

Each Result reports GrossAmount, Capped, Deductible (after phase-out), IsCredit, and Savings (federal tax value), so callers can sum savings across provisions without double-counting caps.

Verification

All figures verified against IRS / Joint Committee on Taxation / Tax Foundation primary sources. Note: energy/EV credits (§25D/§30D/§25E) were TERMINATED by OBBBA for 2026 and are deliberately NOT modeled here.

License

MIT.

Links

• Tax-break calculator suite: https://taxbreakcalc.com/
• Site: https://taxbreakcalc.com/
• Package docs: https://pkg.go.dev/github.com/theluckystrike/obbba-breaks

Documentation

Overview

Package obbbabreaks implements the family of tax breaks governed by the One Big Beautiful Bill Act (OBBBA, 2025) and related permanent provisions: the child tax credit (§24, permanent), the SALT cap (§164(b)(6), $40,400 through 2029 then $10,000 from 2030), the no-tax-on-tips deduction (§224, 2025-2028), the senior deduction (§512, 2025-2028), and the car-loan interest deduction (§163(h)(4), 2025-2028). It is the same math behind the taxbreakcalc.com multi-provision tax-break calculator suite.

Each break is modeled independently with its own cap, phase-out, and (where applicable) credit-vs-deduction character, so a caller can sum Savings across provisions without double-counting caps.

The child tax credit modeled by ChildTaxCredit — the $2,200 per qualifying child amount, the $200,000/$400,000 MAGI thresholds and the $50-per-$1,000 phase-out step — is documented with worked examples and an interactive version at https://taxbreakcalc.com/child-tax-credit-calculator/

Index

• type Break
• type FilingStatus
• type Result
  • func CarLoanInterestDeduction(interestPaid float64, isNewVehicleUSAAssembly bool, fs FilingStatus, ...) Result
  • func ChildTaxCredit(children int, fs FilingStatus, magi float64) Result
  • func SALTCap(stateLocalTaxPaid float64, year int) Result
  • func SeniorDeduction(spouses65 int, fs FilingStatus, magi, marginalRate float64) Result
  • func TipsDeduction(qualifiedTips float64, fs FilingStatus, magi, marginalRate float64) Result

Types

type Break

type Break int

Break identifies a provision.

const (
	BreakChildTaxCredit Break = iota
	BreakSALTCap
	BreakTipsDeduction
	BreakSeniorDeduction
	BreakCarLoanInterest
)

type FilingStatus

type FilingStatus int

Filing status selects per-provision caps and phase-out thresholds.

const (
	Single FilingStatus = iota
	Joint
	HeadOfHousehold
)

type Result

type Result struct {
	Break        Break
	Eligible     bool    // gross amount before cap and phase-out
	GrossAmount  float64 // the provision's full statutory amount
	Capped       float64 // after the per-return/per-child cap
	Deductible   float64 // after MAGI phase-out (the actual claimable amount)
	IsCredit     bool    // true for credits (dollar-for-dollar); false for deductions
	MarginalRate float64 // rate applied to deductions
	Savings      float64 // federal tax value (credit: dollar-for-dollar; deduction: x marginal rate)
}

Result is the per-break outcome.

func CarLoanInterestDeduction

func CarLoanInterestDeduction(interestPaid float64, isNewVehicleUSAAssembly bool, fs FilingStatus, magi, marginalRate float64) Result

CarLoanInterestDeduction returns the §163(h)(4) car-loan interest deduction. Requires isNewVehicleUSAAssembly=true to be eligible (the statute gates the deduction on a new, US-assembled vehicle under 14,000 lbs).

func ChildTaxCredit

func ChildTaxCredit(children int, fs FilingStatus, magi float64) Result

ChildTaxCredit returns the §24 child tax credit for `children` qualifying children at a given MAGI. The full $2,200/child is modeled (the refundable split is upstream bookkeeping).

func SALTCap

func SALTCap(stateLocalTaxPaid float64, year int) Result

SALTCap returns the capped SALT deduction. Pass year to select the cap (2025-2029 -> $40,400; 2030+ -> $10,000).

func SeniorDeduction

func SeniorDeduction(spouses65 int, fs FilingStatus, magi, marginalRate float64) Result

SeniorDeduction returns the §512 additional senior deduction. spouses65 is the count of spouses aged 65+ on the return (1 or 2; for single filers pass 1).

func TipsDeduction

func TipsDeduction(qualifiedTips float64, fs FilingStatus, magi, marginalRate float64) Result

TipsDeduction returns the §224 above-the-line deduction for qualified tips. $25,000 flat per return; MAGI phase-out -100/$1k over $150k/$300k.