Guidance

Horizon Shortfall Scheme Appeals (HSSA): Independent Reviewer terms of reference

Published 30 June 2026

About Horizon Shortfall Scheme Appeals (HSSA)

In September 2024, the government announced the Horizon Shortfall Scheme Appeals (HSSA) process (the process). The process is aimed at providing an independent avenue for Horizon Shortfall Scheme (HSS) applicants to challenge their initial compensation offers in HSS.

The central goal and the overarching principle of the process is to ensure that eligible HSS applicants have the opportunity to receive full and fair redress that restores them to the position they would have been in had it not been for the Horizon-related actions of Post Office Limited.

The process is being run and delivered by the Department for Business and Trade (DBT). The principles governing the process are described in its guidance and principles, which incorporate by reference the HSS Consequential Loss Principles and Guidance and any updates to the HSS Consequential Loss Principles and Guidance as they apply on HSSA provided by DBT from time to time (the guidance). The guidance and this terms of reference (ToR) form the scheme documents.

HSSA Independent Reviewer

On 9 December 2025, DBT appointed the Rt Hon Lord Robert Carnwath of Notting Hill to the position of Independent Reviewer for the process.

The Independent Reviewer may:

• consider Review Applications (defined in the ‘Review Application procedure’ section)
• determine non-review related issues referred to him by DBT via Dentons (the Secretariat)

Non-review related issues may include, but are not limited to, eligibility for the process.

Overriding objectives

The Independent Reviewer (the reviewer) will apply his independent judgement to individual cases, guided by considerations of fairness and in line with the guidance.

Where an appeal is referred to the reviewer, he will assess whether the independent panel’s assessment of the appeal, set out in the panel’s decision paper:

• is substantially inconsistent with the guidance
• reflects a manifest error, procedural irregularity or a substantive error of principle

These points are the review criteria.

Explaining the review criteria

An appeal assessment being ‘substantially inconsistent with the guidance’ means that:

• the independent panel has failed to apply or has misinterpreted the guidance
• this has had a material effect on the panel’s assessment and failed to deliver full and fair compensation

A ‘manifest error’ is an error that is easily demonstrable without extensive investigation, and which has a material effect on the independent panel’s assessment of the appeal. Manifest errors include:

• a decision that went beyond the scope of what the independent panel was permitted to assess
• a decision so irrational that no person, acting reasonably, could have made it
• an error on the part of the independent panel in taking account of clearly irrelevant matters or failing to consider clearly relevant matters
• an error in the mathematical calculation of the compensation sum awarded by the independent panel (but not the assumptions on which that calculation was based, provided that the assumptions are factually correct and relevant)

A ‘procedural irregularity’ is an irregularity in the procedure or decision-making process that the independent panel has used while making its assessment of the appeal. The reviewer may consider procedural irregularities that made a material difference to an assessment. Procedural irregularities might happen if the independent panel has not correctly followed the panel terms of reference or has not properly observed the principles of natural justice in the decision-making process. For the avoidance of doubt, a failure to comply with the timeframes set out in the panel ToR is unlikely to amount to a procedural irregularity.

A ‘substantive error of principle’ is when the independent panel’s assessment of the appeal involved the application of a principle identified in the guidance which is:

• substantively inconsistent with generally accepted legal principles (either existing at the time the guidance was finalised or after that date)
• inappropriate to the case’s circumstances

Review Application procedure

If the applicant or DBT believes the independent panel’s decision paper meets the review criteria, they can apply for review of the decision. This is called a Review Application.

The applicant or DBT must apply for a Review Application within 15 working days of the independent panel issuing their decision paper.

The applicant should complete a request form to apply for a Review Application. The form will be sent out with the independent panel’s decision paper. The completed form should be no more than one page in length. Once completed, the applicant should send the Review Application request form to the Secretariat who will provide a copy to the other party.

Upon receipt of the Review Application request form, a senior lawyer at the Secretariat (the Dentons Senior Lawyer) will provide their view to the reviewer as to whether there is a ‘prima facie’ case. A ‘prima facie’ case is one where, taking the Review Application at face value, the review criteria may be met.

It is up to the reviewer to decide whether there is a prima facie case. Where the reviewer determines that a prima facie case exists, he will identify and specify in writing the particular review criterion or criteria which, in his view, are met on a prima facie basis.

The reviewer will communicate his decision to the case’s Secretariat’s Panel and Reviewer Liaison (P and R Liaison) within 10 working days of the Review Application request being submitted.

If the reviewer concludes that there is not a prima facie case, the P and R Liaison will notify the parties accordingly and the independent panel’s decision paper will stand.

If the reviewer concludes that there is a prima facie case, the Secretariat will write to the parties to notify them accordingly. They will also invite each party to prepare written submissions, which should not exceed 2 pages in length (the Review Submissions).

Assessment of appeals

In reviewing the Review Application, the reviewer will follow the assessment of appeals process set out in this section.

When assessing whether the Review Application meets the review criteria, the reviewer will review the following documentation before making his final determination. He will receive these documents from the P and R Liaison:

• an appeal-specific instruction letter
• a review summary document produced by the Secretariat which sets out a summary of the Review Application
• the Review Application
• a copy of the independent panel’s decision paper
• all documents which the independent panel received in relation to each appeal
• the parties’ review submissions, setting out the parties’ respective positions in relation to applicable review criteria

For the avoidance of doubt, where oral submissions have been provided at a meeting facilitated by the Secretariat, the transcript produced by the Secretariat will be the sole authoritative record of that meeting for the purposes of the review process.

The reviewer will also consider the Review Application alongside any comments on it which he may invite from the independent panel.

For the avoidance of doubt, the reviewer’s remit is limited to the particular heads of loss which meet all 3 of the following criteria:

• determined by the independent panel
• identified by the applicant in their Review Application
• found by the reviewer to meet the review criteria

The reviewer cannot consider heads of loss that were not considered by the independent panel or that were not identified by the applicant in their Review Application.

In assessing Review Applications, the reviewer will be guided by considerations of fairness. He will apply the principles set out in the guidance, in accordance with the overriding objective of achieving full and fair compensation.

In assessing a Review Application, the reviewer can consider previous determinations he has made (whether appeal-specific or not) if the reviewer considers that they are relevant to the appeal under consideration. Where the reviewer has considered his previous determinations in other appeals, this will be recorded in the reviewer’s written determination (defined later in this section).

The reviewer can also consider previous findings and recommendations from the HSS Independent Senior Lawyer (findings), if the reviewer considers the findings relevant to the appeal under consideration and consistent with the scheme documents.

The P and R Liaison will ensure that the reviewer is provided with copies of the findings. Where the reviewer has considered any findings in his assessment of a Review Application, this will be recorded in the reviewer’s written determination. In the event of any inconsistency between a finding and the scheme documents, the scheme documents will prevail.

If the reviewer considers that his assessment of a Review Application is not consistent with a finding, he will promptly notify the P and R Liaison.

If the reviewer is unable to form a view without further evidence (including expert evidence), the reviewer should notify the P and R Liaison as soon as possible. The Secretariat will then seek this further evidence from the applicant or DBT (as appropriate). The instruction of any additional expert evidence will be carried out in accordance with the agreed tariff of reasonable legal costs. The P and R Liaison will inform the parties of the reviewer’s decision and will request that further evidence is provided by a specified date.

After completing his assessment, the reviewer will provide a written determination which will set out:

• whether the independent panel’s decision paper should be upheld
• the reasoning for that decision
• the total compensation award to be paid to the applicant (in the event that the independent panel’s decision paper is not upheld)

The reviewer should provide the written determination to the Secretariat within 2 weeks of receiving the appeal-specific instruction letter, unless he has requested further evidence. If the reviewer has requested further evidence, the written determination will be postponed until after the evidence has been received or the deadline for providing the evidence has passed. If the deadline for providing further evidence passes without the evidence being provided, the reviewer may proceed to issue the written determination.

The Secretariat will issue the written determination to the parties, after which DBT’s offer will follow.

DBT’s offer, based on the written determination, is then final and cannot be further appealed by the parties.

When needed, DBT’s legal representatives can submit clarification questions for the reviewer to the Secretariat within 5 working days of receiving the written determination. This may happen if DBT needs to ensure it is not making payment where it does not have the funding powers to do so. The Secretariat will have the responsibility for determining whether the clarification questions are appropriate for referral to the reviewer.

For the avoidance of doubt, Dentons will not refer clarification questions to the reviewer where they include any submissions, comments or leading questions that put forward a particular position. If the Secretariat does refer clarification questions to the reviewer, the reviewer should endeavour to provide a response as soon as possible.

Reviewer assistance

A standing assistant to the reviewer (the P and R Liaison) will be provided by the Secretariat.

The reviewer may seek such further support from others as may be agreed with the Secretariat.

Communications with DBT and third parties

The reviewer may maintain direct contact with the Horizon Compensation Advisory Board, DBT and the Justice for Subpostmasters Alliance.

Fees

DBT is liable for the reviewer’s fees and disbursements.

Review and approval

This version of the Terms of Reference was approved by DBT on 20 May 2026.