HMRC plans to introduce a new online service for Senior Accounting Officer (SAO) notifications and annual certifications, with launch expected in early 2027. The new service will allow businesses to submit SAO filings through their Government Gateway account.

While many practical aspects are yet to be confirmed, the development is likely to be of interest to SAOs and to finance, tax and governance teams responsible for supporting annual compliance.

Understanding the SAO regime

The SAO regime requires certain large businesses to appoint an individual responsible for ensuring the company has appropriate tax accounting arrangements in place.

Companies must notify HMRC of their SAO where they have turnover exceeding £200m or balance sheet exceeding £2bn, or are part of a corporate group where the aggregated UK companies in the group meet these thresholds. The appointed SAO must provide HMRC with an annual certificate confirming whether the company’s tax accounting arrangements were appropriate.

When the regime was first introduced in 2009, HMRC indicated that the majority of affected companies would be dealt with by HMRC’s Large Business team and have a Customer Compliance Manager (CCM). The notification and certificate would be sent directly to the CCM.

Data obtained through a Freedom of Information Act (FOIA) request by RSM in August 2026 showed that Large Business looks after only 1,540 customers, while HMRC received 51,855 SAO notifications and 52,005 certificates in the year to 31 March 2026. While not a perfect comparison, this could imply that about 96% of SAO certificates are going into a single email inbox (wealthy and midsize SAO compliance). This would be a rate of about 1,000 per week if spread evenly over the year, but is likely to be concentrated at key quarter ends.

Since the pandemic we have seen a significant rise in the number of SAO certificates that are ‘qualified’ because the company did not have appropriate tax accounting arrangements in all respects. This uptick appears to be partly driven by HMRC’s increasingly comprehensive governance guidance, for example the Guidelines for Compliance (GfC). Understanding and applying the GfC can be a challenge for many businesses. We see very few are fully compliant with the best practice laid out.

What we know about HMRC’s announcement

Many businesses with a CCM will have been notified of the change. HMRC describes the new process as administrative rather than legislative, which will bring a structured and standardised approach to SAO reporting to improve efficiency, accuracy and security.

There are no proposed changes to the underlying SAO legislation, including the rules on when penalties may apply for non-compliance.

According to HMRC, the new service has been developed taking account of customer feedback and is expected to include the following features:

• Built-in guidance to help users complete submissions correctly and reduce errors.
• The ability to view previous returns and track submissions.
• Access through existing Government Gateway credentials, without the need for software or new accounts.

Questions still to be answered

The SAO certificate is a personal statutory obligation of the appointed SAO. However, HMRC's announcement suggests that submissions will be made through a Business Tax Account. It is unclear what level of direct involvement will be required from the individual SAO and how access, approval and authorisation processes will operate within larger groups.

Many organisations use external advisers to support elements of their SAO compliance process. HMRC guidance makes it clear that, where email is used, SAOs must personally send certificates to HMRC. HMRC has not confirmed whether agents will be able to prepare or submit notifications and certificates through the new service, or what authorisation arrangements may be required for agent access.

Organisations with a dedicated HMRC CCM may want to understand how the new service will interact with existing compliance processes and communications. Currently, organisations with a CCM submit SAO notifications and certificates directly to the CCM rather than via the standard mailbox. It remains to be seen whether digital submissions will supplement or replace any current reporting practices for these businesses.

Presumably there will be a mechanism to add new companies to the filing, as there is with corporate tax submissions. It will be interesting to see whether the filing history is stored on a company or a group basis.

One of the difficulties of the SAO notification and certification is that it is an individual company requirement which is usually fulfilled with a group submission.

For example, company A is part of the Alpha group. Alpha’s CFO is nominated as SAO and files a notification and certificate for all the Alpha companies, including company A. Company A is then sold to the Beta group, which is also in the SAO regime. The Beta group’s CFO and nominated SAO, not unreasonably, wishes to see the prior year filing made for Company A – but that SAO certificate contains details of other companies too, and potentially details out shortcomings which the Alpha group may not want to share with the Beta group.

In practice, the Beta group normally doesn’t get to see the historical SAO certificate, but if the new portal contains some level of filing history on a per-company basis, this could change.

What HMRC’s new SAO portal means for businesses

We are cautiously optimistic that this will be a positive development. The existing SAO submission process can be hard to track, particularly where filings are submitted by email or managed through multiple stakeholders. A dedicated online service has the potential to improve consistency and visibility for both taxpayers and HMRC. In particular, the ability to view previous returns and track submissions could strengthen governance and provide a clearer audit trail around annual compliance activities.

More importantly, there is a perceived mismatch between the amount of attention taxpayers give to SAO filings and HMRC activity in this area. Many organisations devote significant time and resource each year to supporting the SAO certification. While few of our clients seek more HMRC attention, it is appropriate to see HMRC taking steps to improve the way it processes this information.

The announcement also reflects broader trends: towards the digitalisation of tax administration and HMRC paying more attention to tax governance.

What should UK companies and their SAOs do now?

HMRC has said that there is currently no action required ahead of the launch. However, organisations may wish to use the announcement as an opportunity to revisit their existing SAO governance framework and compliance processes.

A new digital filing platform may create opportunities to streamline internal procedures, clarify responsibilities and improve documentation. Businesses with complex group structures, multiple qualifying entities or reliance on external advisers may particularly benefit from reviewing how future submissions could be managed under the new system.

As further information becomes available, organisations should consider both the technical filing requirements and the broader governance implications of the changes.

How RSM can help with SAO requirements

RSM’s Tax Risk and Governance team supports businesses with all aspects of SAO compliance, including governance reviews, process documentation, controls testing, annual certification support and broader tax risk management.

If you would like to discuss how HMRC's proposed online service may affect your SAO compliance arrangements, please contact Flora Barnes, Louise Brown or your usual RSM adviser.

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