Source: https://guthlabs.ai/docs/instruments/macrs-depreciation-calculator/implementation/

instrument implementation / implementation-contract

# MACRS Depreciation Calculator implementation

A source-bound implementation contract for MACRS Depreciation Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t7-089

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification leaves critical input validation unspecified: non-finite or extreme costs and negative costs can produce Infinity, NaN, or nonsensical negative depreciation unless explicitly rejected. Convention selection also changes the lookup branch and must not be silently inferred or conflated.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "asset_cost_usd": 100000,
    "property_class_years": 5,
    "placed_in_service_date": "2025-03-15",
    "convention": "half-year"
  },
  "expected_outputs": {
    "annual_depreciation_usd": [
      20000,
      32000,
      19200,
      11520,
      11520,
      5760
    ],
    "cumulative_depreciation_usd": [
      20000,
      52000,
      71200,
      82720,
      94240,
      100000
    ],
    "book_value_usd": [
      80000,
      48000,
      28800,
      17280,
      5760,
      0
    ]
  },
  "reference_data": {
    "macrs_5_year_half_year_percent": [
      20,
      32,
      19.2,
      11.52,
      11.52,
      5.76
    ],
    "source_convention": "IRS Publication 946 (2023), Table A-1; standard IRS MACRS half-year convention table"
  },
  "working": "Year 1: $100,000 × 20.00% = $20,000. Year 2: $100,000 × 32.00% = $32,000. Year 3: $100,000 × 19.20% = $19,200. Year 4: $100,000 × 11.52% = $11,520. Year 5: $100,000 × 11.52% = $11,520. Year 6: $100,000 × 5.76% = $5,760. Cumulative amounts: $20,000; $20,000 + $32,000 = $52,000; $52,000 + $19,200 = $71,200; $71,200 + $11,520 = $82,720; $82,720 + $11,520 = $94,240; $94,240 + $5,760 = $100,000. Book value each year is $100,000 minus cumulative depreciation: $80,000; $48,000; $28,800; $17,280; $5,760; $0. The 20%, 32%, 19.2%, 11.52%, 11.52%, and 5.76% entries are exact standard 5-year MACRS table entries."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/macrs-depreciation-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/macrs-depreciation-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/macrs-depreciation-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`