Cheapest fixed energy tariff UK (rolling contract guide)
Find out what “cheapest fixed” really means on today’s UK market, how rolling/evergreen contracts work, and how to compare like-for-like by region, meter type and payment method.
- Clear definitions: fixed vs variable, rolling vs auto-renewal, and what happens at the end of a fix
- Practical checks: unit rates, standing charges, exit fees, and eligibility (smart/prepay/eco7)
- Two realistic cost scenarios with stated assumptions (no “guaranteed” savings claims)
Estimates only. Prices depend on region, meter type and payment method. Always check supplier T&Cs (including exit fees) before switching.
Fast answer: the “cheapest fixed” on a rolling contract depends on your tariff type and region
In the UK, fixed tariffs normally run for a set term (for example 12 months). A rolling contract usually refers to what happens after that term: you either move onto the supplier’s variable (often the Standard Variable Tariff, which is capped by Ofgem’s price cap for many customers), or you roll into another deal if the supplier offers it.
If you’re searching for a “fixed tariff that rolls”, the key is to check what you roll onto at the end of the fix: is it the supplier’s SVT, a new fixed deal, or something else? This varies by supplier and product.
Key takeaways (quick checks that affect “cheapest” most)
- Compare total estimated annual cost (unit rate + standing charge), not just the headline unit rate.
- Region matters: electricity and gas prices vary by distribution area (your postcode).
- Meter type matters: single-rate, Economy 7, smart prepay and traditional prepay can price differently.
- Payment method matters: Direct Debit is often cheaper than pay-on-receipt.
- Exit fees can wipe out a “cheap” deal if you need flexibility.
- Watch end-of-fix terms: what you move onto and whether rates can change immediately after the fixed end date.
Compare fixed tariffs that suit rolling/evergreen needs
If you want the stability of a fixed unit rate but don’t want nasty surprises when the term ends, focus on three things: total estimated cost, exit fees, and end-of-fix outcome.
What to gather (2 minutes)
- Postcode (sets your region)
- Payment method (DD / on receipt / prepay)
- Meter type (single rate / Economy 7 / smart)
- Approx usage (kWh) or current bill
What “rolling” to look for
- No unexpected auto-renewal into a new fixed without consent
- Clear statement of end-of-fix tariff (often SVT)
- Reminders before the fix ends
- Reasonable (or no) exit fees
Important: We’re a whole-of-market comparison service, but availability can still vary by supplier (credit checks, meter compatibility, regional constraints, and whether a tariff is open to new customers).
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How to compare “cheapest fixed” tariffs when you expect to roll at the end
1) Start with your tariff type
Are you dual fuel, electricity-only, or gas-only? Single-rate or Economy 7? Prepay or credit meter? This determines which tariffs you can actually get.
2) Compare annual cost, not just rates
Standing charges vary a lot by region. Two tariffs with the same unit rate can cost different amounts over a year.
3) Check what happens at the end
Most fixes move you onto a variable tariff (often SVT). Set a reminder 4–6 weeks before the end date to review options.
4) Consider exit fees and flexibility
If you might move home, get a heat pump/EV, or change usage, a fee-free or lower-fee tariff can be better even if the rate is slightly higher.
Quick comparison: fixed vs rolling variable (and what to look for)
Use this table to decide what “cheapest” should mean for you: lowest forecast cost, lower risk of price rises, or flexibility to switch again.
| Feature | Fixed tariff (term) | Rolling variable (SVT/evergreen) | What to check |
|---|---|---|---|
| Price certainty | Unit rates/standing charge fixed for the term (subject to T&Cs) | Rates can change; many customers are protected by Ofgem price cap | Are there any clauses that allow changes (e.g. VAT changes, regulatory changes)? |
| Exit fees | Often yes (varies by supplier/tariff) | Usually no | Fee amount per fuel; fee waiver window near end of term |
| End of term | Typically moves onto SVT/variable unless you switch again | Continues indefinitely | What tariff you roll onto and when notifications are sent |
| Who it suits | People who value stability and plan to stay put for the term | People who want flexibility or expect to switch when prices fall | Match term length to your life plans (moving, renovations, EV/heat pump) |
Decision checklist: likely a good fit if…
- You want predictable bills for the next 12–24 months
- You’re happy to set an end-of-fix reminder to review options
- You can pay by Direct Debit and pass a typical credit check (where required)
- You’ve checked exit fees and they’re acceptable for your situation
- Your meter type is supported (single-rate, E7, smart, etc.)
You may prefer a rolling variable if…
- You expect to move home during the next 6–12 months
- You want the freedom to switch quickly if market rates drop
- You’re on (or need) prepay and have fewer fixed options available
- You’re unsure your usage will stay similar (e.g. new EV/heat pump)
- You don’t want to risk paying an exit fee
Two realistic scenarios (illustrative numbers)
These examples show how “cheapest” can change depending on standing charges, usage and exit fees. Figures are illustrative estimates to help you compare, not a promise of what you’ll pay.
Scenario A: low user in a flat (electricity only)
- Assumptions
- Region: example Midlands profile; Payment: Direct Debit; Meter: single-rate
- Usage: 1,800 kWh/yr electricity
- Illustrative comparison
- Fixed: 25p/kWh + 60p/day standing charge ≈ £814/yr
- Rolling variable: 27p/kWh + 50p/day standing charge ≈ £795/yr
- Why: for low usage, a higher standing charge can outweigh a cheaper unit rate.
Scenario B: family home (dual fuel)
- Assumptions
- Region: example Southern profile; Payment: Direct Debit; Meter: credit smart meter
- Usage: 3,100 kWh/yr electricity + 12,000 kWh/yr gas
- Illustrative comparison
- Fixed: Elec 24p/kWh + 55p/day; Gas 6.2p/kWh + 32p/day ≈ £1,651/yr
- Rolling variable: Elec 26p/kWh + 50p/day; Gas 6.8p/kWh + 30p/day ≈ £1,781/yr
- Exit fee check: if fixed exit fees total £100 and you switch after 6 months, the benefit may reduce or disappear depending on your timing.
Math note: Annual cost estimate = (unit rate × annual kWh) + (standing charge × 365). Real bills depend on exact rates, billing periods, and any discounts/fees in the tariff terms.
Costs, exclusions and common pitfalls (UK-specific)
1) Standing charge surprises
A tariff can look cheap per kWh but be expensive overall if the standing charge is high for your region or meter type.
2) Exit fees vs flexibility
If you want the option to switch again quickly, a fixed deal with fees may not be the “cheapest” in practice.
3) Payment method differences
Some tariffs are only available on Direct Debit, and pay-on-receipt prices can be higher.
4) Meter compatibility
Economy 7, smart prepay, and some legacy meters can limit which fixed deals you can switch to.
5) End-of-fix rollover
Most fixed deals roll onto a variable tariff. If you do nothing, your costs may rise or fall depending on the market and price cap changes.
6) Usage changes
Adding an EV charger, electric heating, or hybrid working patterns can change what’s cheapest. Consider tariffs that fit your likely future usage.
Rolling contract wording tip: if a tariff page uses terms like “evergreen”, “standard variable”, “out-of-contract rates” or “default tariff”, treat that as your likely end-of-fix destination unless it explicitly says you’ll move to another fixed deal.
FAQs: cheapest fixed tariffs and rolling contracts (UK)
Is a “rolling contract” the same as a fixed tariff?
Not usually. A fixed tariff has a set end date. “Rolling” commonly means you continue on a variable/evergreen tariff after the fix ends, unless you switch or choose a new deal.
Will I automatically go onto the cheapest deal when my fix ends?
No. Many suppliers move you onto their SVT/variable tariff. That tariff might be competitive, but it isn’t guaranteed to be the cheapest for your home. Set a reminder to compare before your end date.
How do I find the cheapest fixed tariff for my postcode?
Use a comparison that matches your region, meter type and payment method. The cheapest for one postcode can be different elsewhere because standing charges and regional rates vary.
Are fixed tariffs always cheaper than the Ofgem price cap?
No. The price cap limits what many suppliers can charge on SVTs (it’s not a cap on your total bill). Fixed deals can be below, similar to, or above SVT levels depending on market conditions and your region.
Can I switch if I’m in debt to my current supplier?
Sometimes. Rules differ for credit meters vs prepay, and for the size of the debt. If you’re on prepay, you may be able to switch through the Debt Assignment Protocol in some cases. Check supplier and advice guidance before starting a switch.
Do smart meters affect which fixed tariffs I can get?
They can. Some tariffs are smart-only (especially time-of-use). If your smart meter isn’t communicating, you can still usually switch, but certain features (like half-hourly pricing) may not work as intended.
What’s the difference between Economy 7 and single-rate when comparing “cheapest”?
Economy 7 has day and night rates. It’s only likely to be cheaper if a meaningful share of your electricity use happens overnight (commonly quoted as around 30%+, but it depends on your specific rates and standing charge).
How long does switching take in the UK?
Many switches complete in around 5 working days, but it can take longer depending on circumstances (meter issues, incorrect details, or complex setups). You’ll usually keep supply throughout—only the billing supplier changes.
Trust, methodology and sources
Page credits
- Written by
- EnergyPlus Editorial Team
- Reviewed by
- Energy Specialist
- Last updated
- June 2026
How we assess “cheapest fixed tariff” for a rolling-contract query
This guide is editorial (not a live tariff list). When we talk about “cheapest”, we mean the tariff that produces the lowest estimated annual cost for your details, while meeting your constraints (meter type, payment method, and desired flexibility).
- Inputs we assume you’ll need: postcode (region), meter type (single-rate/E7/prepay/smart), payment method, and estimated annual kWh (or a recent bill).
- Comparison basis: estimated annual cost = unit rate × annual usage + standing charge × 365.
- Rolling end-state check: we recommend confirming what tariff applies after the fixed term (commonly SVT/variable), plus notification timings and whether you can leave without penalty near the end.
- Limitations: suppliers can change prices and withdraw tariffs; eligibility varies (credit checks, meter constraints, existing customer exclusives). Regional standing charges and unit rates vary materially, so a “UK-wide cheapest” claim is not reliable.
Editorial promise: We avoid guaranteed savings claims. Any examples on this page are labelled as estimates with stated assumptions, so you can sanity-check your own comparison.
Sources (UK)
- Ofgem (energy regulator, including price cap and switching guidance)
- Citizens Advice energy advice (practical consumer guidance and complaints)
- GOV.UK (official UK government information, including support schemes when available)
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