Tax AMT annual

Alternative minimum tax calculated for a projection year.

Field: Alternative minimum tax Unit: US dollars Basis: nominal dollars Computed by: Engine Status: Complete chain

Appears in: csv (amt); results-table (AMT column when any year has AMT)

Calculation records

• Federal AMT screen Composition record, justified by derivation

  Purpose: Price the planning-grade alternative minimum tax as tentative minimum tax less regular tax, floored at zero.

  Statement: tax/federalTax.ts#amtExemptionAmount, #amtOrdinaryRateTax, #tentativeMinimumTax and #computeFederalTax compute the 2026 single-filer AMT screen as tentative minimum tax on AMTI after its phased exemption, with preferential-rate awareness, less regular tax but not below zero. With no preferential income the tentative tax is 26% through the 28%-rate threshold and 28% above it. Units: nominal USD. Rounding: none stated.

  Formula: E' = max(0, E - q x max(0, A - P)); X = max(0, A - E'); TMT = 0.26 x min(X, T28) + 0.28 x max(0, X - T28); AMT = max(0, TMT - regularTax)

  • A: Alternative minimum taxable income (taxable income plus modeled add-backs) (unit: usd/year) (domain: nonnegative)
  • E: AMT exemption for the filing status, from the tax parameters (unit: usd/year) (domain: positive)
  • P: Exemption phase-out start, from the tax parameters (unit: usd/year) (domain: positive)
  • q: Exemption phase-out rate, from the tax parameters (unit: fraction) (domain: 0 <= q <= 1)
  • T28: 28%-rate threshold on taxable excess, from the tax parameters (unit: usd/year) (domain: positive)
  • regularTax: Ordinary bracket tax plus stacked preferential tax (unit: usd/year) (domain: nonnegative)

  Timing: one tax year

  Rounding: none stated

  Limits:

  • A planning screen, not a full Form 6251 claim: modeled add-backs are the section 63(c) standard deduction or itemized SALT plus the section 151 senior deduction, and the rest of the Form 6251 adjustments are out of scope
  • The pinned rate and exemption helpers are not exported, so the evidence asserts them through computeFederalTax. The worksheet's AMTI of 200,000 and regular tax of 20,000 are not themselves calculator inputs: the test reaches them from real inputs (130,275 of ordinary income, which after the 16,100 standard deduction leaves 114,175 of taxable income and exactly 20,000 of bracket tax, plus 69,725 of advanced amtPreferenceItems, which with the 16,100 standard-deduction add-back makes AMTI 200,000). Any other construction of the same two figures is a different set of inputs.

  Provenance: derived by codex, implemented by claude.

  Independent review: cursor

  Gates (6 of 6 pass): fixture registers a test: pass; pins resolve: pass; families exist: pass; worksheet exists: pass; mutation receipt exists: pass; provenance independent: pass

  Worksheet: federal-amt-screen.md Mutation receipt: federal-amt-screen.mutation.md

  Evidence tests: federalTax.evidence.test.ts

  Implemented in: federalTax.ts

  Is the number of: tax-amt-annual

  Feeds: tax-total-annual

Engine source: engine/src/projection/internal/types/result.ts (YearResult.amt)