Heat network reporting deadlines
Dates from Ofgem's regular data reporting guidance (10 March 2026). Verified 15 September 2026 against the guidance PDF, Tables 1 and 2 and paragraphs 2.3–2.7.
- Registration deadline
- 26 January 2027Verified
- Next window opens
- Q2: 1 October 2026 – 31 October 2026Expected
The window dates above are quoted directly from Ofgem's guidance table — Verified. Whether the digital service accepts submissions in that window is Expected only: Ofgem has said "from Autumn 2026", not an exact date, and as of 30 October 2026 it hasn't publicly announced the first window. Register first regardless — the registration deadline (26 January 2027) doesn't move with this.
Quarterly windows
Data is a snapshot on the last day of the quarter unless the data point says otherwise. You can submit from the first day of the following month until its last day.
| Quarter | Period covered | Submission window | With extension |
|---|---|---|---|
| Q1 | 1 April 2026 – 30 June 2026 | 1 July 2026 – 31 July 2026 | to 31 August 2026 |
| Q2 | 1 July 2026 – 30 September 2026 | 1 October 2026 – 31 October 2026 | to 30 November 2026 |
| Q3 | 1 October 2026 – 31 December 2026 | 1 January 2027 – 31 January 2027 | to 28 February 2027 |
| Q4 | 1 January 2027 – 31 March 2027 | 1 April 2027 – 30 April 2027 (annual return due too) | to 31 May 2027 |
Annual return
Covers 1 April to 31 March. Submitted 1–30 April with the Q4 return (Table 2). Financial resilience data (Table 3) is the exception: it is due in the quarter your accounts are signed off, and no later than 10 months after your financial year end (para 2.6).
Extensions
If you cannot submit by the deadline, you can ask Ofgem for an extension to the last calendar day of the following month (para 2.5). Do not rely on this by default.
Backdating for 2026
Ofgem asks networks to collect data from April 2026 and submit what they have once registered. It will accept the data available for April–June 2026 (paras 2.14–2.15). Ofgem says networks can submit data through its digital service "from Autumn 2026", that it will send a Request for Information to the operators and suppliers of registered networks before the first window opens, and that it will publish further guidance on the reporting process before the first reporting period. Verified against Ofgem, How to prepare for data reporting (checked 30 October 2026).
The July 2026 window passed before the service was ready, and as of 30 October 2026 there is no public sign of the October window opening either. The Request for Information goes privately to registered networks, so if your network isn't registered you won't receive it. Whichever window turns out to be first, expect to backdate to April 2026 on that first submission. Registration (deadline 26 January 2027) is the thing to act on first: the submission windows follow from it, not the other way round.
Upcoming windows
- Q2 2026/27: submit 1 October 2026 – 31 October 2026
- Q3 2026/27: submit 1 January 2027 – 31 January 2027
- Q4 2026/27: submit 1 April 2027 – 30 April 2027, plus the annual return
- Q1 2027/28: submit 1 July 2027 – 31 July 2027
- Q2 2027/28: submit 1 October 2027 – 31 October 2027
- Q3 2027/28: submit 1 January 2028 – 31 January 2028
Add the deadlines to your calendar
Download the deadline calendar (.ics) — every submission window from July 2026 to April 2028 and the 26 January 2027 registration deadline, as all-day events with a reminder the week before. Works with Outlook, Google Calendar and Apple Calendar. Generated from the same dates as this page.
Want an email before each window opens?
Run the free checker and enter your email at the end — about 5 reminders a year, timed to the windows above.