Pillar Two First-Year Compliance: What to Do Now

Pillar Two compliance in its first year is a data and process challenge. Here is a practical guide to GloBE calculations, safe harbours, and filings.

For affected groups, the first year of Pillar Two compliance is less a tax exercise than a data and project-management exercise. The conceptual question, "do we top up to a fifteen percent minimum effective rate in each jurisdiction", is easy to state. Producing the numbers that answer it, on time and defensibly, is where groups are struggling.

Pillar Two compliance has moved from theory to practice. The global minimum tax rules, known as the GloBE rules, are now in force in many jurisdictions, and the first returns and notifications are falling due. Groups that treated the regime as a future problem are discovering that the first year demands work that should have started much earlier.

This guide is a practical orientation for finance and tax leaders facing their first Pillar Two cycle. It does not restate the politics; it focuses on what to do now.

Confirm scope before anything else

Pillar Two applies to multinational groups above a large consolidated revenue threshold, broadly groups with annual revenue of EUR 750 million or more in at least two of the four preceding years, mirroring the country-by-country reporting threshold. Below that, the GloBE rules generally do not apply, although a group approaching the line should monitor it.

If you are in scope, identify which entities are "constituent entities", which jurisdictions they sit in, and which mechanism applies. The regime operates through an Income Inclusion Rule applied at the parent level, an Undertaxed Profits Rule as a backstop, and a Qualified Domestic Minimum Top-up Tax that lets a jurisdiction collect its own top-up first. The interaction of these determines who pays what, where.

Do not assume that operating only in higher-tax countries puts you out of reach. The effective tax rate under GloBE is computed on the regime's own definitions, not your statutory rate, and timing differences, incentives, and credits can pull a jurisdiction below fifteen percent on paper even where headline rates are higher.

The calculation is built on GloBE income, not your accounts

The single biggest first-year shock is that the GloBE effective tax rate is not your accounting effective rate and not your local tax rate. It is a purpose-built calculation.

In outline, for each jurisdiction you compute GloBE income by taking the financial-accounting profit of each constituent entity and applying a long list of prescribed adjustments. You then compute covered taxes, again with adjustments, including the treatment of deferred tax. The jurisdictional effective rate is covered taxes over GloBE income. Where that rate is below fifteen percent, a top-up is due on the excess profit, after deducting a substance-based income exclusion that carves out a return on tangible assets and payroll.

The practical consequence is that you need granular, entity-level and jurisdiction-level data, much of which your existing tax-reporting process was never designed to produce. Deferred tax in particular is a recurring pain point, because GloBE has its own rules on what counts and at what rate.

Lean hard on the safe harbours in year one

The drafters anticipated that full GloBE calculations would be burdensome, and provided transitional relief. The most important is the transitional country-by-country reporting safe harbour, which lets a group treat a jurisdiction as having no top-up tax for a transitional period if it passes one of several tests built largely on existing country-by-country report data and qualifying financial statements.

For many groups, the first-year priority is not to perform full GloBE calculations everywhere. It is to identify which jurisdictions clearly qualify for a safe harbour, take them off the critical path, and concentrate full-calculation effort on the jurisdictions that do not qualify or sit close to the line.

A word of caution: the safe harbours have precise conditions, anti-avoidance features, and a "once out, always out" character in some cases. Qualifying must be documented, not assumed, and the underlying country-by-country data must itself be reliable.

Map the filings and deadlines now

Pillar Two creates new obligations distinct from your ordinary corporate-tax returns. Broadly, groups must prepare a GloBE Information Return, the standardised global calculation, and make notifications and any top-up tax filings in the relevant jurisdictions, including domestic minimum tax returns where a jurisdiction has enacted one.

Crucially, the first GloBE Information Return is generally due on an extended deadline measured from the end of the first reporting fiscal year, longer than subsequent years. That extension is generous but also a trap: it encourages groups to defer work that, given the data effort, cannot safely be left late. Domestic minimum tax payment deadlines may arrive sooner than the information return.

We map, jurisdiction by jurisdiction, what must be filed, by whom, where, and when, and which entity in the group carries the filing responsibility. Local implementation varies, so the calendar is genuinely group-specific.

The real project is data and ownership

Across first-year engagements, the same lessons recur.

Data sourcing is the long pole. Pulling entity-level financial data, tax data, deferred-tax detail, and asset and payroll figures into one consistent model, on the GloBE basis, takes longer than the calculation itself. Start from the source systems, not the consolidated accounts.

Ownership must be assigned. Pillar Two sits awkwardly between tax, group reporting, and finance systems. Without a named owner and a clear escalation path, it falls between teams.

Audit and accounts are affected too. Top-up tax has financial-statement consequences, and auditors will expect to see the supporting calculations and safe-harbour evidence. The compliance file and the accounts disclosure are two sides of the same work.

Get the position documented. Even where no top-up is due, the analysis showing why, the safe harbour relied upon, or the calculation supporting a nil result, is what protects the group on review.

Build for repeatability, not heroics. Many groups survive year one through brute effort, with spreadsheets assembled by hand under deadline pressure. That is not sustainable. Because Pillar Two recurs annually and the transitional safe harbours expire, the data model, the entity mapping, and the deferred-tax workpapers should be built once, properly, and refreshed each year. The groups that invest in a repeatable process in year one spend dramatically less in year two, and they carry far less risk of an error that an auditor or a tax authority later unwinds.

How HPT helps

We help in-scope groups run a disciplined first Pillar Two cycle: confirming scope, identifying which jurisdictions qualify for transitional safe harbours, building the GloBE data model where full calculations are needed, mapping the filing and notification calendar across jurisdictions, and coordinating with auditors and local advisers. Where a group is below the threshold or comfortably protected by safe harbours, we keep the effort proportionate.

If you are facing your first Pillar Two filings and want a clear plan of action, we would be glad to help you build one.