Comparison · Business energy
Choosing a business energy contract: fixed, flexible or pass-through
Last updated 25 October 2026 · 2 sources listed · Reading time about 3 minutes
Short answer
Fixed contracts set the energy price for the term, flexible or purchase-in-tranches contracts let you buy in steps to average market timing, and pass-through contracts expose you to wholesale movement and itemised third-party charges. Choose by budget certainty needs, ability to absorb volatility, load profile and the clarity of non-commodity charges. Broker involvement and regulation differ by country.
Who this is for: A small or mid-sized business renewing a commercial electricity or gas contract and comparing structures.
What to evaluate
Budget certainty needs
A business with thin margins may need predictable energy cost.
How to check: Review how much an energy cost swing would affect your margin.
Contract structure
Fixed, flexible and pass-through arrangements allocate market risk differently.
How to check: Ask which cost components are fixed and which pass through. Check whether a contract can be terminated or novated when you sell, close or relocate a site, since stranded commitments are a frequent source of unexpected cost for growing and shrinking businesses alike.
Non-commodity charges
Network, policy and capacity charges form a major part of the bill and may change.
How to check: Request a bill breakdown showing each component and how it is treated.
Volume tolerance
Contracts often assume expected volumes with penalties outside bands.
How to check: Check tolerance bands and the charges for consuming more or less.
Contract length and termination
Long terms reduce flexibility if you move or change operations.
How to check: Find termination rights and any rollover or deemed-contract provisions.
Supplier and broker transparency
Commissions can be built into unit rates.
How to check: Ask for written confirmation of any broker commission in the rate.
Comparison
| Structure | Good when | Watch out for |
|---|---|---|
| Fixed price | Budget certainty matters | No benefit if market falls |
| Flexible purchase in tranches | You can manage timing of purchases | Needs active monitoring and risk policy |
| Pass-through | You can absorb volatility and want transparency | Bill swings and variable charges |
| Deemed or out-of-contract rate | Short bridging period | Typically unfavourable rates |
Decision worksheet
Rate up to three options against this guide’s own criteria. It runs in your browser and saves only on this device. It is a thinking aid, not a recommendation.
1. Have you checked each criterion?
0 of 6 criteria checked.
2. Compare options (0 = fails or unknown, 3 = meets it well)
| Criterion | |||
|---|---|---|---|
| Budget certainty needs | |||
| Contract structure | |||
| Non-commodity charges | |||
| Volume tolerance | |||
| Contract length and termination | |||
| Supplier and broker transparency | |||
| Total (max 18) | 0 | 0 | 0 |
Questions to ask before you commit
- Which components are fixed and which can change?
- What are the volume tolerance bands and penalties?
- How are network and policy charges treated?
- What notice is needed to terminate or renew?
- Is there a broker commission and how much does it affect the rate?
- What happens if I move premises?
- How is credit assessed and is a deposit required?
- How are disputes handled and which regulator oversees you?
Typical trade-offs
Fix for a longer term
- Upside
- Predictable budgeting
- Downside
- Locked in if conditions change
Buy in tranches
- Upside
- Averages market timing
- Downside
- Requires oversight and governance
Pass-through
- Upside
- Transparent costs
- Downside
- Exposed to volatility
Common mistakes
- Missing the renewal window and rolling onto an unfavourable deemed rate. Ask each supplier to state in writing how volume tolerance works, meaning what happens if actual use rises or falls compared with your forecast, because penalties for swings differ greatly between contract structures.
- Ignoring volume tolerance clauses.
- Not asking about broker commission.
- Assuming all charges are fixed when only the commodity is.
- Signing for a site you may leave.
Related questions
What is a deemed contract?
If you occupy a premises without agreeing a contract, or your contract lapses, the supplier may apply a default rate that is often less favourable. Regulation differs by country. Avoid it by managing renewal dates and starting negotiation well before the end of your term.
Do I need a broker?
Brokers can save time and access multiple suppliers, but they may be paid via commission built into your unit rate. Ask for disclosure in writing and compare at least a direct quote. Check whether the broker is registered with a relevant body where one exists.
What are non-commodity charges?
These are costs beyond the energy itself, such as network use, capacity, metering and policy levies. They can be a large share of the bill and are sometimes passed through at changing rates. Ask for a breakdown and whether each is fixed for the term.
How early should I begin renewal?
Start several months before expiry, since suppliers may require notice windows and market conditions shift in the meantime. Gather usage data, check any changes at the site such as new equipment or altered hours, and compare contract structures rather than only unit rates. Check your contract and regulator guidance for notice requirements, because missing a window can roll you onto a default rate. Keeping a diary of renewal dates for each site helps larger organisations.
Sources and further reading
These pages were reachable when we last checked. They informed definitions and rules referred to above; they do not endorse this guide. Where rules differ by country, check the authority for your location.
- Ofgem business energy information — Ofgem, retrieved 27 October 2026
- Energy Explained — U.S. Energy Information Administration, retrieved 27 October 2026
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