Fixed vs variable business energy contracts

Choosing the right business energy contract can have a big impact on your operating costs. Fix your rate, and you get a level of certainty and bill stability. Go variable, and you get flexibility but also risk. Get it right, and you protect your business from price volatility. Get it wrong, and you could face bills that blow your budget.

In 2026, this decision matters more than usual. TNUoS network charges — the fees energy suppliers pass on to fund the transmission grid — have risen by more than 60% since April 2026. 

On top of that, new regulated asset base (RAB) nuclear levies have been introduced, adding further cost pressure across the market. Together, these changes mean wholesale and non-commodity energy costs are heading up regardless of what happens to gas and electricity spot prices.

That context matters when you're deciding between a fixed and variable contract. This guide explains how each type works, what suits different businesses, and what to look for before you sign.

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In this guide to fixed vs. variable business energy contracts…

• Fixed contracts lock your unit rate for the contract term, giving budget certainty
• Variable tariffs move with the wholesale market - potentially cheaper sometimes, but riskier
• Flexible or blend-and-extend deals can suit higher-usage businesses
• Your risk appetite and how stable your energy usage is should drive the decision
• Market conditions in 2026 make fixed deals the safer default for most SMEs

What is a fixed contract?

A fixed business energy contract sets your unit rate - the price per kilowatt hour (kWh) of energy you use - for a defined period. That's typically between one and three years. Whatever happens in the energy market during that time, your rate stays the same.

This gives you predictability. You can model your energy costs into your budget and know they won't change because of market movements. That said, your total bill can still vary month to month depending on how much energy you actually use. A fixed rate doesn't mean a fixed bill.

Fixed contracts are the most common type of business energy deal in the UK and are offered by all major suppliers.

What is a variable contract?

A variable contract means your unit rate can go up or down at any time, in line with movements in the wholesale energy market. These contracts often have no fixed end date, running on a rolling basis until you switch or the supplier changes the terms.

The appeal is flexibility. If wholesale prices fall, your costs could follow. There's no long lock-in period, and switching is usually easier. But prices can rise quickly and without warning, and there's little you can do about it mid-contract, other than switch to a fixed-rate.

Variable tariffs are sometimes called out-of-contract rates or deemed contracts, when a business hasn't actively chosen them. For example, after a fixed deal expires without renewal or if you've moved into new premises without arranging an energy contract. These default rates are typically among the most expensive available.

You can find out more in our guide to out-of-contract and deemed rates.

Fixed vs variable vs flexible at a glance

	Fixed	Variable	Flexible
Price certainty	High	Low	Medium
Market exposure	None	Full	Partial
Risk level	Low	High	Medium
Contract length	1–3 years	Rolling	1–3 years
Best for	Stable budgets	Short-term flexibility	Higher usage businesses

The pros and cons of fixed contracts

Before deciding whether a fixed rate contract is best for your business, it's worth weighing up the pros and cons.

What's good about fixed-rate contracts

• Budget certainty. You know your unit rate for the full contract term. That makes it easier to forecast energy spend, set budgets, and avoid surprises.
• Protection from price rises. If wholesale costs go up, your rate doesn't. But the TNUoS increases and nuclear levies may still be variable, so always ask your broker or supplier about these.
• Easier financial planning. Lenders, accountants, and investors often prefer predictable cost structures. A fixed energy rate removes one variable from your P&L.

What to watch out for

• No benefit if prices fall. You're locked in, so a drop in wholesale prices won't reduce your rate during the contract term.
• Longer commitment. Most fixed deals run for at least 12 months. Some businesses find that restrictive, particularly if they're growing, downsizing, or planning to move premises.

Pros and cons of variable contracts

Before deciding whether a variable contract is best for your business, it's worth weighing up the pros and cons.

What's good about variable contracts

• Flexibility. No long-term lock-in means it's easier to switch if a better deal comes along or your circumstances change.
• Potential to benefit from price falls. If wholesale energy prices drop, a variable rate can follow them down.
• Shorter notice periods. Variable contracts often require less notice to exit compared to fixed deals.

What to watch out for

• Price volatility. Rates can increase at short notice, making costs hard to predict. This is a real problem for smaller businesses with tight margins.
• Poor value by default. Businesses that end up on variable (out-of-contract) rates without actively choosing them often pay above-market prices. If you're on a variable rate, check whether it's competitive.
• Hard to budget around. Finance teams and business owners often find variable energy costs difficult to manage, particularly when they fluctuate frequently.

Which businesses suit fixed contracts?

Fixed contracts work best for businesses that value predictability over the chance of savings. That covers most small and medium-sized enterprises (SMEs).

They're particularly well-suited to businesses that:

• Have steady, predictable energy usage
• Operate on tight margins where cost surprises cause real problems
• Are planning ahead and need reliable cost forecasts
• Want protection from the current market volatility in 2026

Retail, hospitality, office-based businesses, and professional services typically fall into this group. If your energy bill is a meaningful line item and you can't easily absorb increases, fixing gives you peace of mind.

Which businesses suit variable contracts?

Variable tariffs are better suited to businesses that can absorb cost fluctuations and are comfortable taking on more risk in exchange for flexibility.

They may work for businesses that:

• Expect wholesale prices to fall in the near term
• Need short-term cover only. For example, while waiting for a better deal
• Have energy costs that represent a small share of overall expenses
• Have in-house expertise to monitor the market and act quickly

That said, for most SMEs in the current market, the case for a variable contract is weak. With prices under upward pressure in 2026, the chance of benefiting from falls is limited, and the risk of sharp rises is real.

Hybrid and flexible options

Some suppliers offer contracts that sit between fully fixed and fully variable. These are sometimes called flexible contracts or structured procurement deals, and they're more commonly available to businesses with higher energy consumption.

The idea is to fix a portion of your energy cost while leaving the rest exposed to market movements. Done well, this can balance stability with the potential for savings. Done badly, it adds complexity without meaningful benefit.

Blend and extend

A blend and extend arrangement lets you renegotiate an existing fixed contract before it ends. Rather than waiting out your current term, you combine your existing rate with a new market rate, blend them into a single revised price, and extend the contract length.

This approach can be useful if your current rate is above the current market and you want to move to better pricing without the disruption of switching suppliers. It's often used as a negotiation tool when rates have moved significantly since you originally fixed.

Not all suppliers offer blend and extend, and the terms vary considerably — so it's worth comparing what's on offer rather than accepting the first proposal.

Pass-through contracts

With a pass-through contract, non-commodity costs, including network charges, balancing charges, and government levies, are billed separately at cost rather than bundled into your unit rate. This makes pricing more transparent and can work in your favour when those costs are stable or falling.

But non-commodity costs are rising sharply, including TNUoS charges and new nuclear levies. A pass-through contract means you absorb those increases directly. For most SMEs, that makes pass-through a higher-risk option in the current market than a standard fixed deal.

You can find out more in our guide to business energy tariffs.

Is a longer fixed term worth it in 2026?

With ongoing market uncertainty, 24 and 36-month fixed deals are currently being priced at levels close to 12-month spot rates. For businesses, that's an unusual opportunity - you can lock in price stability for two or three years without paying significantly more than a shorter deal.

For most SMEs, this makes a longer fixed term worth serious consideration right now. The cost of certainty has rarely been this low.

Fixed and variable tariff FAQs

Still unsure whether to go fixed or variable? Check out the answers to our most frequently asked questions.

Which contracts are cheaper long-term?

It depends on what the market does. Fixed contracts tend to offer better value when prices are rising or volatile, because you're protected from increases. Variable contracts can work out cheaper if prices fall significantly, but prices are hard to predict, and this comes with risks. For most SMEs, fixed deals provide more reliable long-term value even if they're not always the cheapest in hindsight.

Are variable contracts risky for SMEs?

Yes, they can be for most smaller businesses. Variable rates can rise quickly and without warning, which makes planning difficult. Businesses with tight margins or a high dependence on energy are particularly exposed. Unless you have a specific need for flexibility, a fixed deal is usually the lower-risk choice in the current market.

Can I switch from fixed to variable?

You can switch once your fixed contract ends. Unlike domestic energy, business energy contracts generally can't be ended early.

What industries benefit from flexible pricing?

Energy-intensive sectors, including manufacturing, food processing, logistics, and large hospitality groups, may be best placed to benefit from flexible contracts. These businesses typically have more control over when and how they use energy, which means they can respond to price signals and adjust consumption accordingly. For most standard SMEs, that level of active management isn't practical.

Are flexible contracts widely available?

Flexible contracts are available from some suppliers, but they're mainly aimed at businesses with higher energy consumption, typically above 100,000 kWh per year. Smaller businesses usually have access to fixed and variable deals only. If you're looking for flexible options, it's worth asking suppliers directly what's available for your consumption level.

Do suppliers charge exit fees on fixed business energy contracts?

Ending a business energy contract before its end date isn't as straightforward as leaving a domestic energy contract early, and you may need to pay the remaining balance or the full contract value. You might be able to end a contract early without penalty if you go out of business or are moving premises. Find out more in our guide - Change of Tenancy - Moving business premises and your energy contract.

How often do variable prices change?

It varies by supplier. Some review and adjust variable rates monthly, while others may change them more or less frequently depending on wholesale market movements. Your contract terms should specify how much notice the supplier must give before changing your rate. If you're on a variable tariff, it's worth checking this and keeping an eye on your bills for changes.

Is price hedging available for small businesses?

Full hedging strategies, where you buy energy forward in tranches to average out your cost, are generally only available to businesses with significant consumption, typically large commercial or industrial users. Some suppliers offer simplified versions for mid-sized businesses, but for most SMEs it's not a practical option. The nearest equivalent for smaller businesses is a fixed-term contract, which provides similar cost certainty without the complexity.