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First published: 25 March 2026 · Status: PROPOSED
In our process of understanding the current status of RECCo’s Tariff Interoperability programme we’ve collated and updated their public reference material to get a better view.

This published spec is updated with our proposed changes, changes are © 2026 Auth Energy Ltd

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What is it?

The Tariff Interoperability (TI) API is a GB government-mandated standard that requires electricity suppliers to publish their tariff pricing data via a consistent API. It is defined under the Retail Energy Code (REC) and driven by the Smart Secure Electricity Systems (SSES) Programme at DESNZ. The goal is to let Energy Smart Appliances (EVs, heat pumps, batteries) and third-party optimisers automatically read tariff prices and optimise energy use — without consumers having to manually input their tariff details into every app and device.

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Two tiers of access

TierWhoAuth
Public Tariff Pricing DataAny TI User — no registration requiredNone
Consumer Specific Tariff InformationRegistered TI Users (RTI Users) with active consumer consentOAuth 2.0

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Flow 1 — Discovering Public Tariff Data

Any application or device can retrieve public tariff pricing without authentication. The typical flow is two steps: look up the supplier’s endpoint from the central register, then fetch their tariffs.
When public tariff data alone is insufficient to identify a consumer’s exact pricing (e.g. their tariff varies by meter type or has a bespoke bolt-on), an RTI User can request consumer-specific data — but only with explicit consumer consent via OAuth 2.0.
The consent mechanism described below (Option 1 — standalone OAuth) is under active review. RECCo is considering Option 2, which would defer consumer-specific access to the Consumer Consent Service (CCS) and deliver only public tariff data in Phase 1a. See the consent options section below.

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Flow 3 — Webhook Event Notifications

Once an RTI User has active consumer consent, the supplier pushes event notifications to the RTI User’s registered webhook URL whenever something changes. RTI Users must verify the payload signature before acting.
Dynamic tariffs do not generate tariff.update events. RTI Users must poll proactively, using the valid_from / valid_to datetimes on rate windows to know when to refresh.
Last modified on March 28, 2026