HMRC Pillar 2 Software Update: What Accounting Firms and CFOs Must Check Now

HMRC updated its authorised software list for Pillar 2 Top-up Taxes on 5 August 2026, expanding the range of commercial tools approved to submit Domestic Top-up Tax (DTT) returns, Multinational Top-up Tax (MTT) returns, and the GloBE Information Return (GIR). For accounting firms advising large corporate groups and for in-house CFOs managing the compliance timetable, the update carries direct operational consequences: any software not on HMRC's list cannot be used to file, and gaps in coverage across the three submission types create real filing risk. The practical questions to answer now are straightforward but pressing.

What Pillar 2 Top-up Tax Actually Requires

The Pillar 2 framework, enacted in UK law, imposes a global minimum effective tax rate of 15% on the largest corporate groups. Where a group's effective rate in any jurisdiction falls below that floor, a top-up charge applies. The UK charges this through two routes: DTT, which applies where the low-taxed entity itself sits in the UK, and MTT, which applies where a UK-headquartered group has low-taxed operations overseas.

The three filing obligations at stake

Groups within scope must manage three distinct submission types:

• UK Tax Return: the primary return for DTT and MTT liability, submitted through HMRC-authorised commercial software.
• Overseas Return Notification: required where a group has elected to file a Qualified Domestic Minimum Top-up Tax (QDMTT) return in another jurisdiction, giving HMRC the relevant notification.
• GloBE Information Return (GIR): the detailed information return covering the group's full global Pillar 2 position. HMRC has now confirmed that this is also known as the "information return" in its earlier guidance updates.

A fourth route exists for groups that fall below the threshold: Below Threshold Notifications can be submitted either through commercial software or directly via the HMRC Pillar 2 Digital Service.

Why software authorisation matters

HMRC's position is unambiguous: groups must use commercial software that has obtained the required authorisation from HMRC to submit returns and notifications. HMRC will not recommend one provider over another and takes no responsibility for difficulties arising from a chosen tool. If a software provider encounters technical problems, the group or its agent must resolve those directly with the supplier. That places the selection decision, and its consequences, squarely on the accounting firm or the CFO.

What Changed on 5 August 2026

The 5 August update is the latest in a series of incremental expansions to HMRC's approved software lists. The guidance page records the history of each change, which gives advisers a useful audit trail of which providers entered the approved pool at which point.

Additions and amendments across submission types

The August 2026 update made two types of change. First, the list of software providers authorised for UK Tax Returns and Overseas Return Notifications received one amendment. This suggests an existing provider updated or expanded its authorised scope rather than a new entrant joining the list. Second, the list of software suppliers covering the GloBE Information Return (information returns) received one new addition, continuing the pattern from earlier in the year when that list was built out progressively from a standing start.

Looking at the full revision history recorded in the GOV.UK guidance, the GIR-capable software list has been the more actively developed of the two, having seen multiple new additions across successive updates. The UK Tax Return and Overseas Return Notification list has been more stable, with amendments rather than net additions dominating recent changes. That distinction is operationally relevant: a firm whose software was authorised early for UK Tax Returns may not yet be covered for GIR submissions, and the two lists are maintained separately.

Practical Implications for Accounting Firms

The software selection decision for Pillar 2 is not a one-time exercise. Because HMRC's approved lists are updated on a rolling basis, a tool that was not yet authorised for GIR submissions at the start of a client engagement may since have gained that authorisation, or an existing provider may have had its scope amended. Firms need a process for tracking these changes rather than relying on a snapshot review done at engagement outset.

Cross-referencing software coverage against all three submission types

The immediate action for any firm advising a Pillar 2-affected group is to map each client's current software arrangement against all three submission categories: UK Tax Return, Overseas Return Notification, and GIR. The lists on GOV.UK are maintained separately, and a provider appearing on one list does not automatically appear on both. Where a client's chosen software covers only the UK Tax Return but not the GIR, a gap exists that must be resolved before the GIR filing deadline.

Firms acting as agents face the same constraint as the group itself: submission must go through authorised software, and the responsibility for contacting the software provider about errors or difficulties sits with the firm, not HMRC. Building clear contractual terms around that responsibility in engagement letters is advisable.

Agent-submitted returns and the authorisation chain

The guidance confirms that submissions can be made by the group itself or by an agent on its behalf. Where a firm acts as agent, the software it uses must carry the authorisation, not just the software the client uses internally. Firms running their own compliance platforms or working through third-party tools need to verify their own authorisation status, not only the client's.

Implications for CFOs at In-Scope Groups

For CFOs of large corporate groups, the Pillar 2 software question sits at the intersection of tax compliance, financial reporting, and procurement. Choosing software that is not yet authorised for all required submission types is not a minor administrative issue: it can prevent a return from being accepted, which in turn creates late-filing exposure.

Aligning software procurement with the filing calendar

Groups whose accounting year aligns with the calendar year will be working towards their first GIR submissions now, and procurement decisions made months ago need to be stress-tested against the current authorised list. Where a group's chosen system was on HMRC's list at procurement but has since had its scope amended, that change needs to be understood: does the amendment expand or narrow what the software can submit?

CFOs should also note that HMRC's guidance explicitly covers the option of submitting Below Threshold Notifications through the Pillar 2 Digital Service directly, without commercial software. For groups that are just above the threshold in some jurisdictions but well below in others, this distinction between which submissions need software and which can go through the digital service affects the overall compliance architecture.

Financial statement considerations

Pillar 2 top-up taxes carry their own accounting treatment requirements under both IFRS and UK GAAP. IFRS Accounting Standard IAS 12, as amended following the IASB's response to the Pillar 2 rules, introduced a temporary mandatory exception to recognising and disclosing deferred tax assets and liabilities arising from Pillar 2 legislation. Groups must disclose their exposure to Pillar 2 top-up taxes in their financial statements even where the temporary exception applies. The software used for filing the tax return is a separate system from the accounting ledger, but the two need to be reconciled: the GIR draws on data that originates in the financial statements, and any inconsistency between the two creates risk at audit.

For groups with digital asset holdings, the intersection of Pillar 2 and FASB's emerging work on crypto asset accounting standards adds another layer of complexity. The effective tax rate calculation underpinning the Pillar 2 charge depends on the accounting treatment of assets. Where crypto assets are carried at fair value under IFRS, unrealised gains feed into accounting profit, which in turn affects the effective rate computation. Groups holding material digital asset positions should ensure their Pillar 2 software can handle the inputs that flow from a fair value accounting approach rather than a historical-cost one.

The Broader Software Compliance Context

The Pillar 2 software approval process is part of a wider pattern of regulators and tax authorities moving compliance submission processes onto purpose-built digital infrastructure. Across the EU, DAC9 escalations are already pressing firms to upgrade their cross-border tax reporting capabilities, and the GIR under Pillar 2 is one of the most data-intensive cross-border tax submissions ever required of corporate groups.

The GIR requires a jurisdiction-by-jurisdiction breakdown of revenue, profit, taxes paid, and effective rates across every territory in which the group operates. Assembling that data from multiple source systems, mapping it to the GIR schema, and submitting it through HMRC-authorised software is a process that requires early preparation. Groups that have treated Pillar 2 as a tax team problem, rather than a data and systems problem shared across finance and IT, are likely to find the GIR the hardest part of the compliance cycle.

What HMRC will and will not do

HMRC's stance is clearly set out: it maintains the authorised list, it operates the Pillar 2 Digital Service for specific submission types, and it will not recommend one software product over another. Any technical issues with the chosen software are between the group (or its agent) and the software supplier. HMRC will not intervene to resolve software errors, and a return that fails because of a software issue does not receive automatic relief from late-filing consequences.

That means the due diligence work sits entirely with the adviser or the group. Testing a chosen system against HMRC's technical specifications before a live submission, not on the filing deadline, is the only way to manage this risk.

Frequently Asked Questions

Which corporate groups are within scope of the UK Pillar 2 Top-up Taxes?

The Domestic Top-up Tax and Multinational Top-up Tax apply to the largest corporate groups, based on the Pillar 2 threshold set in UK legislation enacting the global minimum effective tax rate of 15%. Groups below the threshold can submit a Below Threshold Notification rather than a full tax return, and that notification can go through either commercial software or the HMRC Pillar 2 Digital Service directly.

Does the same software need to cover both the UK Tax Return and the GloBE Information Return?

Not necessarily. HMRC maintains two separate authorised lists: one for UK Tax Returns and Overseas Return Notifications, and one for the GloBE Information Return. A software provider can appear on one list but not the other. Groups must ensure their chosen software is authorised for each submission type they need to make, which may mean using more than one tool or confirming that a single supplier covers both lists.

What happens if a group submits through software that is not on HMRC's authorised list?

HMRC requires submission through authorised commercial software. A submission made through a tool that has not obtained the required authorisation is unlikely to be accepted. The group or its agent would need to resubmit using an authorised provider, which creates late-filing risk if the error is discovered close to or after the deadline.

How does the GloBE Information Return interact with financial statements prepared under IFRS?

The GIR draws on jurisdiction-level financial data that originates in the group's consolidated and local accounts. Under IFRS, the IASB introduced a temporary mandatory exception to recognising deferred tax for Pillar 2 purposes, but disclosure of Pillar 2 exposure is still required. Groups with assets carried at fair value, including crypto assets under fair value accounting, need to ensure the effective tax rate calculation used in the GIR correctly reflects the accounting treatment applied in the financial statements.

Can an accounting firm agent use different software from the client when submitting on the client's behalf?

Yes, an agent submitting on behalf of a group must use software that is itself authorised by HMRC for the relevant submission type. The authorisation attaches to the software, not to the entity using it. A firm using its own compliance platform must confirm that platform's authorisation status independently of what the client uses internally.

Source: HMRC / GOV.UK