---
title: "GloBE Top-Up Tax & QDMTT Allocation Calculator"
method: POST
path: "/v1/tools/compute_globe_topup_tax"
tags: ["TODO_TAGS_REVIEW", "TODO_AP2_EXPORT_REVIEW"]
---

# GloBE Top-Up Tax & QDMTT Allocation Calculator

`POST /v1/tools/compute_globe_topup_tax`

## Request

- Base URL: `https://ainumbers.co`
- URL: `https://ainumbers.co/v1/tools/compute_globe_topup_tax`
- Auth: none declared

OECD Pillar Two GloBE top-up tax calculator: per-jurisdiction substance-based income exclusion (SBIE), effective tax rate (ETR), and top-up-rate/top-up-amount, then allocates the top-up across QDMTT, IIR, and UTPR, applying the OECD Side-by-Side Safe Harbour (approved/declassified 5 January 2026) when the caller declares a Central Record listing of a Qualified SbS Regime, a Filing Constituent Entity election, and a fiscal year on or after 1 January 2026 -- when it applies, Top-up Tax is deemed zero for both the IIR and the UTPR. Ports the calculation from tools/473-globe-etr-jurisdiction-calculator.html and tools/474-topup-tax-qdmtt-calculator.html into one provable kernel. SBIE payroll/asset rates and the 15% minimum rate are OECD-published transitional table values pinned behind a constants_version field -- a rate change is a version bump, never a silent recompute. Jurisdiction-level QDMTT enactment/rate and the Central Record listing are caller-supplied, never vendored. KNOWN-WRONG (comment only, not behaviour, recorded 2026-08-17 per ART9-CITATION-FIX-1): the kernel source at chaingraph/kernels/art-365-compute-globe-topup-tax.kernel.mjs line 49 cites the SBIE transitional rates as 'Art. 9.1' -- the correct citation is Art. 9.2 (Art. 9.1 is Tax Attributes Upon Transition; Art. 9.2 is the Transitional relief for the Substance-based Income Exclusion, per research/ART9-NUMBERING-CONFIRM-1.md and research/ART9-NUMBERING-DENY-1.md). This node is sealed (compute_proof_ready: ready) so the kernel comment is left uncorrected per SO #36 -- no GPU re-prove for a comment. The kernel's behaviour is correct and cleared ART-365-SIDEBYSIDE-1 with zero divergences; fix the comment only if art-365 is ever legitimately re-proved for another reason.

**Tool URL:** https://ainumbers.co/chaingraph/art-365-compute-globe-topup-tax.html

## Request body

- object
  - `central_record_sbs` unknown[], required
    - unknown
  - `fy` number, required
  - `jurisdictions` unknown[], required
    - unknown
  - `parent_hq` unknown, required
  - `sbs_election` boolean, required

## Response `200`

Successful tool execution result

- object
  - `aggregate_etr` number
  - `central_record_sbs` string[]
  - `constants_version` string
  - `fy` integer
  - `globe_min_rate` number
  - `jurisdictions` object[]
    - `assets` integer
    - `below_min_etr` boolean
    - `etr` number
    - `iir_collected` integer
    - `income` integer
    - `income_net_sbie` number
    - `jur` string
    - `payroll` integer
    - `qdmtt_collected` number
    - `qdmtt_enacted` boolean
    - `qdmtt_rate` number
    - `sbie` number
    - `sbie_payroll_rate` number
    - `taxes` integer
    - `top_up_amount` number
    - `top_up_rate` number
    - `utpr_collected` integer
  - `low_etr_count` integer
  - `note` string
  - `parent_hq` string
  - `regulatory_basis` string
  - `sbs_election` boolean
  - `total_iir_collected` number
  - `total_income` integer
  - `total_qdmtt_collected` number
  - `total_taxes` integer
  - `total_top_up_tax` number
  - `total_utpr_collected` integer
  - `us_exempt` boolean

---

[API](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite.md) · [All operations](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/llms.txt) · [OpenAPI document](https://skmtc.dev/ainumbers/apis/ainumbers-co-fintech-intelligence-suite/revisions/b462e4f5bb28?raw)