The market for Pillar Two software is young and fragmented. Some tools are purpose-built for GloBE; others are existing tax platforms with a Pillar Two module bolted on. The difference matters — particularly at filing time, when an auditor asks to see the workings behind a top-up tax figure and you need to trace it to source in seconds, not days.
The core requirements
At minimum, Pillar Two software must handle six things correctly:
- GloBE Income calculation — financial accounting net income, adjusted for all Art. 3.2 items, per constituent entity.
- Adjusted Covered Taxes — current tax, deferred tax (recast at 15%), and all Art. 4 adjustments.
- Safe harbour testing — all three transitional CbCR tests per jurisdiction, with correct grain (jurisdictional, not entity-level) and correct thresholds by year.
- SBIE carve-out — declining payroll and tangible asset rates per year, correctly applied to the net book value base.
- Top-up tax allocation — IIR, UTPR and QDMTT treatment per jurisdiction and ownership chain.
- GIR output — ~480 data points assembled correctly, exportable as OECD-schema-aligned XML.
The audit trail question
A calculation engine that produces the right number is necessary but not sufficient. Tax authorities and external auditors will want to verify the workings — and in many jurisdictions, the GIR is subject to the same documentation standards as a transfer pricing local file. That means every intermediate figure needs to trace back to a source input, with the OECD rule cited at each step.
Bolt-on audit trails — where the tool computes first and then reconstructs the trace — are fragile. If the computation and trace run on different code paths, they will drift. The only defensible audit trail is one that is generated as a by-product of computation itself.
Multi-entity, multi-jurisdiction scale
Most MNE groups in scope have between 10 and 200 constituent entities across 5 to 30 jurisdictions. Pillar Two software needs to handle this scale without requiring manual jurisdiction-by-jurisdiction runs. Safe harbour pre-screening should run across the full entity footprint in a single pass, with jurisdiction-level aggregation handled automatically.
Collaboration and workflow
GIR preparation is a team exercise — preparers, reviewers and senior sign-off, often across multiple firms. Good Pillar Two software supports @mention queries, flagged calculation steps, and partner approval workflows, with a full comment trail that is retained alongside the computation. This replaces the email and spreadsheet threads that otherwise become the de facto audit trail.
Filing obligation tracking
Beyond the computation itself, groups need to track GIR submission deadlines, IIR notification windows and QDMTT self-assessment due dates across every in-scope jurisdiction. The best tools auto-generate these obligations from the entity footprint and enacted jurisdiction rules, colour-coded by urgency.
Pillar2OS is built around these requirements from the ground up. Try it free with five entities — no card required.