EnergyPlus · May 2026
Cheapest variable energy tariff in the UK this month (May 2026)
A variable tariff means the price moves over time. In the UK there are two flavours: the default (standard variable) tariff capped by Ofgem each quarter, and tracker tariffs that update daily based on wholesale prices. In May 2026 the cheapest variable option is almost always a tracker — Octopus Tracker and E.ON Next Pulse have averaged sub-cap most days this month — but they carry daily price risk and need a SMETS2 smart meter. This page shows where the cheapest variable tariffs sit right now and when a variable beats a fix.
Editorial information, not financial advice. Prices and policy can change — always confirm against the supplier and Ofgem.
Cheapest variable tariff this month — May 2026 at a glance
The default (standard variable) tariff is capped at the April–June 2026 Ofgem cap. Trackers like Octopus Tracker and E.ON Next Pulse have averaged roughly 5–15% below the cap on most days in early May 2026 (cap-tested to never exceed the cap). Trackers need a SMETS2 smart meter and carry daily volatility — useful for households comfortable with that. Households who want certainty should pick a 12-month fix at 2–6% below cap on typical use.
Quick checklist (May 2026):
- Default (capped) tariff: Apr–Jun 2026 cap — the most expensive everyday rate.
- Tracker tariffs: ~5–15% below cap most days in early May 2026, daily volatility.
- Trackers require SMETS2 smart meter and 30-minute reads.
- Q3 2026 cap announced late May — variable rates move with it.
- Compare averages, not single-day rates — trackers are about long-term position.
- Last updated
- May 2026
- Reviewed by
- Energy Specialist
- Audience
- UK households & small businesses
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Fixes of 12/18/24/36 months trade certainty for flexibility.
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Cheapest variable UK energy tariff this month (May 2026)
A clear, current overview to help you choose with confidence.
Default vs tracker vs fix
The default (standard variable) tariff is the standard rate you roll onto if you don't switch — capped each quarter by Ofgem. Tracker tariffs update daily based on wholesale prices and are tested to never exceed the cap. Fixes lock a single rate for 12, 18 or 24 months.
How trackers price
Octopus Tracker uses a published formula tied to day-ahead wholesale gas and electricity, plus network and policy costs. E.ON Next Pulse uses a similar formula. Both publish the next day's prices in the evening, so you can plan. Both apply a cap test — daily price will never exceed the Ofgem cap unit rate.
When variable beats fix in May 2026
Trackers beat the cheapest 12-month fix on average if wholesale stays flat or falls over the 12 months. In early May 2026 trackers have averaged sub-cap by ~5–15%, while the cheapest 12-month fix is 2–6% below cap. If you can stomach daily moves, trackers are likely cheaper — if you want a flat number, fix.
Why the Ofgem cap still matters
The cap is the ceiling for the default tariff and the cap-test floor for trackers. The Q3 2026 cap is announced late May and takes effect 1 July. A rising cap pulls tracker ceilings up; a falling cap pulls them down. Either way, variable tariffs respond — that's the point.
Compare like-for-like
Indicative May 2026 view for a typical UK dual-fuel customer. Run a personalised comparison with the form on this page.
| What to compare | Typical range (May 2026) | Notes |
|---|---|---|
| Default (capped) tariff | Reference baseline | Maximum allowed by Ofgem on standard variable tariffs. |
| Octopus Tracker | Averaged ~5–15% below cap in early May 2026 | Daily wholesale-linked rate, cap-tested. SMETS2 required. |
| E.ON Next Pulse | Averaged ~5–15% below cap in early May 2026 | Similar formula to Octopus Tracker. SMETS2 required. |
| British Gas StreamLine / variable green | At-cap to ~3% below cap | Standard variable with a green badge. Same cap framework as default. |
| 12-month fix (for comparison) | ~2–6% below cap on typical use | Locks rate for the year — pick this if you want certainty over variability. |
How to pick the cheapest UK variable energy tariff this month (May 2026)
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1. Confirm your meter type
Single-rate, Economy 7 or SMETS2 smart. Trackers need SMETS2 with half-hourly reads.
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2. Find your annual kWh for both fuels
Use last year's bill or supplier app — the most recent 12 months of electricity and gas.
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3. Compare trackers vs default
Look at the tracker's published 30-day average vs the cap unit rate for your region. A tracker that averages 5–15% below cap will roughly save 5–15% on the unit-rate portion of your bill.
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4. Decide on volatility tolerance
Trackers move daily. If you check prices daily and can shift load, a tracker is cheaper. If you want one flat number, switch to a fix instead.
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5. Run a whole-of-market comparison
Use the form on this page — it surfaces every variable and tracker for your postcode.
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6. Apply and submit opening reads
Switching takes 5 working days. Submit electricity and gas opening reads on day one.
Common pitfalls to avoid
The most frequent issues we see when households and businesses act on what looks like a good deal.
- Picking a tracker without a SMETS2 smart meter — it won't price you correctly.
- Judging a tracker on a single-day rate — they're about average over months, not days.
- Staying on the default (cap) variable when a sub-cap variable or fix is available.
- Switching to a green-badged variable thinking it's cheaper — most are at cap, not below.
- Ignoring how the next cap will pull your variable rate — Q3 cap announcement is late May.
Frequently asked questions
What's the cheapest variable energy tariff in the UK this month?
In May 2026 the cheapest variable tariffs are trackers — Octopus Tracker and E.ON Next Pulse have averaged roughly 5–15% below the April–June 2026 cap on most days this month. Both need a SMETS2 smart meter and pass through daily wholesale moves. The default (standard variable) tariff sits at the cap and is the most expensive everyday rate.
What's the difference between a default tariff and a tracker?
A default (standard variable) tariff is the standard rate set by your supplier, capped each quarter by Ofgem. A tracker is also variable but updates daily based on a published formula tied to wholesale prices, with a daily cap test so it never exceeds the Ofgem cap unit rate.
Are tracker tariffs cheaper than fixed tariffs?
On average over a year, trackers are usually cheaper when wholesale stays flat or falls. In early May 2026 trackers average roughly 5–15% below cap, while the cheapest 12-month fixes sit 2–6% below cap. The cost of a tracker is daily volatility and the need for a SMETS2 meter.
Do I need a smart meter for a tracker tariff?
Yes — SMETS2 with half-hourly reads is required for Octopus Tracker, E.ON Next Pulse and most tracker products. Legacy meters can't report fast enough to price each day correctly.
How often do tracker tariff prices change?
Daily, in most cases. Octopus Tracker publishes the next day's prices in the evening. Cap-tested — the daily price will never exceed the Ofgem cap unit rate.
When is the next Ofgem cap update?
The Q3 2026 cap (Jul–Sep) is announced late May 2026 and takes effect 1 July. After that, Q4 (Oct–Dec) is announced late August, and Q1 2027 (Jan–Mar) is announced late November.
Can I switch from a fixed tariff to a variable mid-term?
Yes — you can switch any time, but you'll pay the exit fee on the original fix (usually £50–£75 per fuel) unless you're in the final 49 days of the fix. A no-exit-fee fix avoids this.
Are green variable tariffs cheaper than the default?
Some are, some aren't. Standard variable 'green' tariffs (matched via REGOs) usually price at the cap — same framework as the default. Specialist green variables priced below cap exist but you have to compare carefully.
Trust, methodology and sources
Page governance
- Written by
- EnergyPlus Editorial Team
- Reviewed by
- Energy Specialist
- Last updated
- May 2026
How we keep this page current
We refresh this page each month against the latest Ofgem cap, supplier tariff changes and current scheme guidance. Worked numbers are illustrative; quotes you receive via the comparison form are personalised to your meter and postcode.
Editorial independence: our priority is clarity and like-for-like comparison. Where commercial relationships exist, options are still presented on suitability and the information available at the time.
Reputable UK sources we reference
- Ofgem — energy price cap
- Ofgem — types of energy tariff
- Citizens Advice — compare energy tariffs
- Energy Saving Trust — smart meters
If you spot anything that looks out of date (a rule change, a new scheme), please contact EnergyPlus so we can review and update this page.
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