Your Big Four Advisor Sent You an HTML GIR File. Here Is Why You Cannot Upload It to HMRC
The Workflow Gap Between Calculation and Submission That Nobody Warned You About
Your external tax advisor has done the work. The GloBE calculations are complete. The ETR figures are checked. The document landed in your inbox – clean, formatted, professional. It might be an HTML file. It might be a PDF. It might even be a beautifully structured Excel workbook with jurisdiction-level breakdowns and safe harbour flags.
None of it can be submitted to HMRC.
Not because the calculations are wrong. Because the format is wrong. And the gap between having a completed GIR calculation and being able to actually file it with HMRC is exactly where many first-cycle groups are losing critical time right now, with June 30 days away.
This blog explains what that gap is, why it exists, and what needs to happen to close it before the deadline. If you need a reminder of what the penalties for missing June 30 look like, read our blog on what happens if you miss the June 30 Pillar Two GIR deadline first.
What the GIR Actually Is
The GloBE Information Return is the standardised annual return that MNE groups must file under the Pillar Two rules. It contains the information tax authorities need to assess ETR calculations, evaluate top-up tax liability and verify safe harbour positions across every jurisdiction where the group operates.
The GIR is not a form you fill in and sign. It is a structured data return. It contains jurisdiction-level financial data, constituent entity details, GloBE-adjusted accounts, ETR calculations, safe harbour elections, top-up tax computations and entity-level attributes – all in a precisely defined structure.
For a broader introduction to the Pillar Two framework and how the GIR relates to CbCR obligations, read our BEPS Pillar Two and CbCR multi-jurisdiction filing guide.
What Your Advisor Actually Delivered
When a Big Four firm or specialist tax advisor completes a GIR engagement, their output is typically a calculation model. It shows the ETR by jurisdiction, flags safe harbour positions, models top-up tax scenarios and presents the group’s Pillar Two position in a format that is designed to be reviewed, signed off and approved by the client’s tax team.
That output is almost always in one of the following formats:
- A structured HTML document showing jurisdiction-level data
- A PDF of the completed GIR template
- An Excel workbook with the underlying calculations
- A proprietary tool output exported for client review
Every one of these is a review format. Not a submission format.
The document your advisor sent you is the input to the filing process. Not the filing itself.
What HMRC Actually Requires
You must use compatible software to make your Pillar 2 Top-up Taxes submissions. This is confirmed on GOV.UK’s guidance on how to report Pillar 2 Top-up Taxes.
HMRC does not have a portal where you upload a PDF or HTML document. There is no form-fill interface that accepts Excel. The GIR must be submitted in the OECD-prescribed XML schema format, transmitted programmatically via HMRC’s API using software that has gained the required production credentials from HMRC.
The OECD published the GIR XML schema user guide in January 2025. While the XML schema was primarily designed to facilitate the exchange of GIR information between tax administrations, the XML schema can also be used for domestic GIR filings, to the extent permitted under the domestic laws of the relevant jurisdiction.
In the UK, HMRC has mandated the use of this XML schema for GIR submission. The schema defines the precise structure, element names, data types, percentage formats, entity identifiers and validation rules that every submitted GIR must conform to. A file that does not conform to the schema will be rejected.
What Your Advisor Delivered vs What HMRC Accepts
| Format | Purpose | Can be submitted to HMRC |
| HTML GIR document | Client review and sign-off | No |
| PDF of GIR template | Internal approval and record keeping | No |
| Excel calculation model | ETR modelling and scenario planning | No |
| Proprietary tool export | Advisor workflow output | No |
| OECD-compliant XML via authorised software | HMRC submission | Yes – only this |
Why the Gap Exists
This is not a failing of your advisor. It is a structural feature of how the Pillar Two regime was designed.
The OECD deliberately separated the calculation layer from the submission layer. The GIR template – the document your advisor works with – is a standardised data capture tool. The XML schema is the machine-readable transmission format. They contain the same underlying data but serve completely different functions.
Most Big Four engagement models are built around the calculation layer. Producing a calculation output, reviewing it with the client and signing off on the group’s Pillar Two position is their core service. Transmitting that output to HMRC in OECD-compliant XML via an API-connected platform is a separate capability that not all advisors offer directly.
The groups that are running out of time right now are the ones that assumed the calculation output was the filing. It is not. The calculation is step one. The XML conversion and submission is step two. And step two requires software that HMRC has authorised.
What Needs to Happen Between Calculation and Submission
The workflow from completed calculation to valid HMRC submission involves the following steps:
Step 1 – Data extraction The structured data from the advisor’s calculation output needs to be extracted into a format that a GIR XML generation tool can ingest. This typically means mapping the advisor’s jurisdiction-level data to the corresponding elements in the OECD GIR schema.
Step 2 – XML generation The extracted data is loaded into an OECD-compliant XML generation platform. The platform maps each data point to the correct element in the GIR schema – constituent entity identifiers, jurisdiction ETRs, top-up tax amounts, safe harbour elections, GloBE status flags and all other required fields.
Step 3 – Schema validation The generated XML is validated against the OECD schema before submission. This checks that every required element is present, that data types conform to schema rules, that percentage values are within valid ranges and that entity identifiers are correctly formatted. A file that fails validation is rejected at the point of submission.
Step 4 – HMRC API submission The validated XML is transmitted to HMRC via the Pillar Two API using software that holds production credentials from HMRC. The submission returns a confirmation and an obligation status update on the group’s Pillar Two dashboard.
Step 5 – ORN or GIR confirmation If the GIR is filed centrally in another jurisdiction, the ORN is submitted to HMRC separately confirming where the GIR was filed. Both the ORN and the GIR submission must be complete before the June 30 deadline.
From Calculation Output to Valid HMRC Submission
| Step | What happens | Who handles it |
| 1. Data extraction | Advisor’s output mapped to OECD GIR schema elements | Bridging software or internal tax tech team |
| 2. XML generation | OECD-compliant XML generated from mapped data | HMRC-authorised Pillar Two software |
| 3. Schema validation | XML checked against OECD schema before transmission | Software pre-validation layer |
| 4. HMRC API submission | Validated XML transmitted via HMRC Pillar Two API | HMRC-authorised software with production credentials |
| 5. ORN submission | Overseas Return Notification filed if GIR filed centrally | Same authorised software |
Have the calculations. Need the XML?
DataTracks Oxbow takes your GIR calculation data and generates validated OECD-compliant XML ready for HMRC submission. We handle the full workflow from data input to filed confirmation. One of 10 HMRC-recognised Pillar Two software providers on GOV.UK.
The OECD GIR XML Schema: What It Actually Requires
The GIR XML schema is an IT format designed to support the automatic exchange of GloBE Information Return data as part of the implementation of the Global Minimum Tax. Since the data transmitted via the XML schema may contain errors, such as those arising from incorrect file preparation or incomplete or inaccurate records, the OECD has developed a common XML schema to enable validation and error reporting.
The schema is precise and unforgiving. Key requirements include:
- Constituent entity data must use ISO 3166-1 country codes for residence
- Percentage values must be expressed in decimal format between 0 and 1, with a maximum of four decimal places
- Amounts must be rounded to the nearest full number for GIR reporting purposes, while unrounded figures are used for the underlying GloBE calculations
- The message type field must contain only “GIR” – no other value is valid
- Every constituent entity, JV and JV subsidiary must be individually identified within the schema structure
A calculation output in HTML or Excel contains this data. But it is not structured in the way the schema requires. The conversion from one to the other is not a copy-paste exercise. It requires a platform that understands both the advisor’s output format and the OECD schema structure.
What DataTracks Oxbow Does
DataTracks Oxbow is built specifically to bridge this gap. The platform ingests your GIR calculation data – whether from an advisor’s output, an ERP system or an internal model – and generates fully validated OECD-compliant XML ready for HMRC submission.
DataTracks is one of 10 software providers listed on GOV.UK’s Choose the right software for Pillar 2 Top-up Taxes page as having gained the required HMRC production credentials. The platform handles UK Tax Return submission, Overseas Return Notifications and GIR generation.
For groups managing Country-by-Country Reporting under BEPS Action 13 alongside their GloBE obligations, Oxbow maintains data consistency between CbCR and GloBE datasets from the same platform – protecting the transitional safe harbour position that depends on that alignment.
The process is straightforward. Your data goes in. Validated OECD XML comes out. HMRC submission is confirmed.
What to Do If You Are in This Position Right Now
If you have a completed GIR calculation from your advisor and have not yet filed with HMRC, here is exactly what to do:
Confirm your filing route first. Is your group filing the GIR directly with HMRC or centrally in another jurisdiction with an ORN to HMRC? If you are filing via ORN, confirm the GIR has already been submitted in the overseas jurisdiction before submitting the ORN. Submitting an ORN before the GIR is filed creates an invalid ORN and does not remove your UK filing obligation.
Get the calculation data into a submission-ready format. Send your advisor’s output to DataTracks. We extract the relevant data, map it to the OECD GIR schema and generate the XML. Most clients are through this step within one to three business days.
Submit before June 30. The HMRC Pillar Two filing portal has been open since May 19, 2026. There is no technical barrier to filing now. The only barrier is having the XML.
Do not wait for your advisor to tell you the submission is done. Ask them specifically whether the GIR has been submitted to HMRC in OECD XML format via HMRC-authorised software. If the answer is anything other than yes, the filing is not complete.
Have the calculation. Need the filing? DataTracks handles the rest.
DataTracks Oxbow converts your GIR calculation data to OECD-compliant XML and submits to HMRC. One of 10 providers recognised on GOV.UK. June 30 is days away.
Frequently Asked Questions
Why can I not just upload my advisor's HTML file to HMRC?
HMRC does not have a portal that accepts HTML, PDF or Excel for GIR submissions. The GIR must be submitted in OECD-prescribed XML format via HMRC-authorised software using the Pillar Two API. Source: GOV.UK – How to report Pillar 2 Top-up Taxes.
What is the OECD GIR XML schema?
Does my Big Four advisor not handle the submission as well as the calculation?
Not always. Many advisor engagements are scoped around the calculation layer – completing the GIR template, checking ETRs and advising on safe harbour positions. The XML generation and HMRC API submission is a separate technical step that requires authorised software. Always confirm with your advisor whether their scope includes the actual HMRC submission or only the calculation output.
How quickly can DataTracks convert my calculation output to OECD XML?
Most clients complete the data extraction, XML generation and validation within one to three business days of providing the calculation output. For urgent cases with the June 30 deadline approaching, contact the DataTracks team directly at enquiry@datatracks.co.uk.
What is the difference between filing the GIR and submitting an ORN?
If your group files the GIR directly with HMRC, you submit the full OECD XML GIR via authorised software. If your group files the GIR centrally in another qualifying jurisdiction, you submit an ORN to HMRC confirming where it was filed. The ORN is only valid if the GIR has already been submitted in the overseas jurisdiction at the time the ORN is filed.
Does DataTracks handle both the GIR XML and the ORN submission?
Yes. DataTracks is authorised by HMRC for both UK Tax Return submissions and Overseas Return Notifications. The platform handles the full Pillar Two submission workflow. Source: GOV.UK – Choose the right software for Pillar 2 Top-up Taxes.
