Source: https://guthlabs.ai/docs/instruments/irs-contribution-limit-lookup-401k-ira-hsa/implementation/

instrument implementation / implementation-contract

# IRS Contribution Limit Lookup (401k/IRA/HSA) implementation

A source-bound implementation contract for IRS Contribution Limit Lookup (401k/IRA/HSA); 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**: t7-104

**Effect**: Computation or source lookup only

## Input and validation requirements

An unsupported tax year produces an undefined lookup result, and age-date interpretation can select different catch-up branches unless the convention is explicitly specified.

## 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": {
    "account_type": "401k",
    "tax_year": 2024,
    "age": 49
  },
  "expected_outputs": {
    "annual_limit_usd": 23000,
    "catch_up_limit_usd": 0,
    "total_maximum_usd": 23000
  },
  "reference_data": {
    "account_type": "401k",
    "tax_year": 2024,
    "base_limit_usd": 23000,
    "catch_up_age": 50,
    "catch_up_limit_usd": 7500,
    "source_convention": "IRS 2024 published retirement-plan limits, IRS Notice 2023-75"
  },
  "working": "Age 49 is below the inclusive catch-up threshold of 50, so catch_up_limit = 0. annual_limit = 23,000. total_maximum = 23,000 + 0 = 23,000 USD."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/irs-contribution-limit-lookup-401k-ira-hsa/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/irs-contribution-limit-lookup-401k-ira-hsa/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/irs-contribution-limit-lookup-401k-ira-hsa/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`