The short answer is that the best time to switch business energy suppliers is usually as soon as your switching window opens. This can be up to 12 months before your contract ends. You can agree a new deal then, and it starts the day your old one ends. 

The other good time is straight away, if you're on deemed or out-of-contract rates.

Energy prices are always changing. The timing of your energy switch can make a big difference to the rates you pay. Although you can often start a business energy comparison months before your current contract's end date, the terms of commercial energy contracts mean the switch won't happen until your current contract ends. 

But that doesn't mean your contract's end date should completely dictate when you switch. It's worth running an energy price comparison as soon as your switching window opens.

Confused? Our Bionic guide explains everything you need to know.

Five-point summary of when to switch business energy suppliers

• You can usually compare and agree a new business energy deal as soon as your switching window opens, often one to six months before your contract ends.
• If you're on deemed or out-of-contract rates, you could switch business energy suppliers at any time, without an exit fee.
• The switch itself usually takes around five working days under Ofgem's Faster Switching rules, but it only goes live when your current contract ends.
• Your supplier can only block your switch for specific reasons, such as unpaid debt or a contract that hasn't ended yet.
• Bionic compares quotes from trusted UK suppliers and tracks your renewal date, so you don't get rolled onto pricier rates.

Key business energy switching terms

Before we get into when you should switch, it's worth getting to know some of the key terms.

• Switching window - Set by your contract, this is the period when you can compare and agree a new business energy deal before your current one ends.

1. Out-of-contract rates - A type of default tariff your supplier charges when your fixed contract ends and you haven't agreed a new one. They're usually much higher than negotiated rates.
2. Deemed rates - A type of default tariff you pay when you use energy at a business premises without agreeing a contract, such as after moving in.
3. An objection - A formal block a supplier places on your switch. Suppliers can only object for set reasons, such as unpaid debt.
4. Faster Switching - An Ofgem reform that moved energy switches onto a new central system in July 2022, cutting switch times to days rather than weeks.

Can you switch business energy suppliers? 

When it comes to commercial gas and business electricity, there’s actually a limited timeframe in which you can compare deals and make the change. 

But there's never really a bad time to switch energy suppliers. What business owner doesn't want an easy way to cut their overheads? So if you're after a new energy deal, the first thing to do is find out when your switching window opens.

Most UK businesses are very small. At the start of 2025, there were 5.7 million private sector businesses in the UK. Around 4.3 million had no employees other than the owners. If you run your business solo, missing a renewal date is easy. That's why timing your switch well could save you both money and admin. 

Signing up to Bionic's Digital Renewals service means we do all the work for you at renewal, so you never again pay out-of-contract rates.

When is the best time to switch business energy suppliers?

A lot depends on how long is left on your contract and the tyep of contract you're on. But here are some things to consider.

When your switching window opens

A switching window is a designated time when you can compare business energy rates and sign a new contract. 

The length of your switching window depends on your supplier and the type of energy deal you’re on, but it usually starts between one and six months before your current deal is due to expire. 

Don’t worry if you’re unsure when your current contract ends - your supplier will write to let you know your deal’s end date. Any correspondence will also include your supplier’s renewal offer - the rates you’re offered at this point are unlikely to be among the most competitive, so you should always compare what else is on offer before signing up for another deal.

Once your current deal enters its switching window, you can contact Bionic’s tech-enabled experts to compare deals and negotiate exclusive rates on your behalf. 

Although you can’t actually switch at this point, you can agree to a new deal and lock in your rates to help protect against price volatility. This means your new deal will start as soon as your old one ends, and you can avoid being rolled over onto your supplier’s more expensive out-of-contract rates.

When you’ve moved into new business premises

Although switching to a better business energy deal probably won’t be your top priority when moving your business into a new property, it’s something you need to sort out at the first opportunity. This is because all businesses are placed onto a contract known as ‘deemed rates’ when they move into a new place, and these rates are always more expensive than any you’ll find on a negotiated deal.

The good news is that you can switch business energy suppliers at any time if you’re on deemed rates, without any notice period and with no termination fees. If you’ve recently moved into a new property, check out our guide to moving business premises.

When your contract has already ended

If your fixed deal has ended and you're on out-of-contract rates, you could switch business energy supplier straight away. You don't need to wait for a switching window. Every day on these rates could cost you more than a fixed deal.

Find out more in our guide to avoiding Deemed, out‑of‑contract rates and expensive contract gaps at renewal.

As soon as possible

Energy prices are always changing, but they very rarely drop. 

"You might think it’s not worth comparing deals as soon as your switching window opens, simply because you won’t benefit from your new rates until your current contract ends and your new one takes over. 

But that's often not the case. Signing up for a new deal at the earliest possible opportunity means you can lock in your rates and avoid price volatility. This can be especially important if you have a long switching window, as prices can increase significantly over six months." - Les Roberts, Senior Content Manager at Bionic

What to check during your energy contract review

When reviewing your business energy contract, getting the lowest possible rates will be your first priority. But that's not the only thing you should consider. Here are some things to look out for as part of your review:

• Contract structure - Understand whether you have fixed vs. pass-through components. Fixed-rate tariffs provide budget certainty, while flexible or time-of-use tariffs may suit businesses with predictable consumption patterns or the ability to shift usage to off-peak periods.
• Standing charges and non-commodity costs - These charges have evolved significantly with regulatory changes. Verify that standing charges, network fees (TNUoS, DUoS), environmental levies, and government charges are correctly applied and competitive.
• TCR banding and capacity settings - Under the Targeted Charging Review, incorrect banding or capacity settings inherited from previous tenants or based on outdated usage data can result in unnecessarily high charges. Request verification from your supplier.
• Deemed and out-of-contract rates - If you've moved into new business premises without arranging a contract, you'll be on deemed rates—typically the most expensive tariffs available. Similarly, expired fixed-rate contracts automatically roll onto out-of-contract rates with higher unit costs.
• Contract length - Consider whether shorter contracts (1-2 years) offer flexibility or if longer agreements (3-5 years) provide better rate security during volatile market periods.
• Green energy options - If environmental credentials matter to your business, compare green energy tariffs or renewable energy certificates (REGOs) that demonstrate your commitment to sustainability.
• Broker fees - Since 1 October 2024, suppliers must show any broker commission in your contract's principal terms, whatever your business size. Check this figure before you sign. At Bionic, we always fully disclose how much commission we make from your chosen supplier before you sign a contract.

Working with a business energy broker or consultant can simplify contract reviews, particularly for businesses with multiple sites or complex energy needs. They can identify cost-saving opportunities in contract structures that aren't immediately obvious from standard tariff comparisons.

Business energy switch and contract basics

Before you compare business energy quotes, take a quick look at some business energy switch basics, including the terms of your contract and your rights as a commercial energy customer.

What is your switching window?

Your switching window is the earliest point at which you can compare prices and arrange a new deal. Your supplier should let you know when this window opens. As standard, this will be 90 days before the end date of your contract, but timescales can differ, so always check your contract. 

If you run a microbusiness, bear in mind that the rules around switching are different to those of other SMEs.

However long your switching window, your supplier must give you written confirmation of it and also explain their automatic renewal policy and the terms of their deemed contracts.

What happens when your business energy contract ends?

When your business energy contract ends, you'll usually roll onto your supplier's more expensive out-of-contract rates. To avoid overpaying, you should consider running a comparison and switching supplier, or moving to a better deal with your current supplier.

Depending on your supplier, you may be rolled onto a new fixed-term contract – often with slightly higher rates – although this is becoming less common. Alternatively, you might be moved on to a 30-day rolling contract until you formally organise a new one.

When will you get your new energy contract?

There are several obligations that every energy supplier has to meet. Once you sign up for a business energy contract, it’s the responsibility of the new supplier to contact you within ten days outlining the full terms and conditions of your contract. This includes when your switching window opens, their automatic renewal policy and the terms of their deemed contracts.

No one likes to read the T&Cs, but it’s worth taking the time to read through and understand them, not least because business energy contracts don't offer a cooling-off period. This means you can’t change your contract once you’ve signed on the dotted line, so it can literally pay to make sure everything is as it should be.

Are switching rules different if you run a micro business?

A micro business is a type of business energy customer that Ofgem gives extra protection. That includes clearer contract terms and access to the Energy Ombudsman.

If you run a micro business, things are slightly different, and you have a bit more time and flexibility when it comes to changing your supplier. 

Ofgem rules state that micro businesses need to give their supplier just 30 days' notice before switching. 

The regulator also states that 60 days before a fixed-term contract ends, your supplier must also get in touch to let you know how much energy you use each year, along with details on how the price of your current deal compares with the new contract prices it’s offering.

If your energy bills are less than £1,000 a month, you’ll most likely be classed as a micro-business, but Ofgem defines a micro business as one that meets at least one of the following:

• Employs fewer than 10 employees (or their full-time equivalent) and has an annual turnover or balance sheet no greater than €2 million; or
• Uses no more than 100,000 kWh of electricity per year; or
• Uses no more than 293,000 kWh of gas per year.

Ready to switch? Leave your postcode in the box on the right to start your comparison.

Can your business energy supplier block your switch?

Your supplier does have the right to block your switch, but only in the following specific circumstances:  

• If you owe money to your supplier. If you owe more than £500 for gas or £500 for electricity, your supplier can block your switch until the debt has been repaid.
• If your current fixed-term contract hasn’t ended. Once you sign up for a business energy deal, you can’t switch to a new deal until this one has expired. Even so, you can compare deals as soon as your switching window is open.
• You don’t pass your new supplier’s credit check - You may not realise it, but business energy suppliers always run a credit check to help work out whether or not you are low risk or high risk before they enter into a contract with you so that they can have some assurances that you’re unlikely to default on your energy tariff. 

Can you change your energy supplier if you’re in debt?

Before you compare business or domestic energy deals, remember that if you’ve been in debt with your supplier for more than 28 days, you won’t be able to switch until the debt is paid off. 

Will your energy be turned off if your business energy switch gets blocked?

The simple answer is no. It’s very rare for a supplier to resort to the lengths of disconnecting a customer’s energy supply.

Disconnection is usually a supplier's last resort, and most will only do this when all other avenues have been exhausted in trying to recover debt from a customer over a considerable time. Before disconnecting your premises, your supplier must make a reasonable effort to contact you via email, phone and letter.

As well as an outstanding balance, your supplier has the legal right to disconnect your supply if you have unlawfully altered your premises' energy meter. An unlawful alteration would be any modification that changes the function of the meter, most commonly to bypass the meter and reduce the amount you’re being charged for energy.

Provided you are not in debt and you have not altered your meter in any unlawful way, then there is very little chance that your supply will be cut off during a switch – even if either supplier chooses to block the switch. 

If your switch is blocked and your current contract ends, your supply won't be cut off. Instead, your current supplier will move you onto more expensive out-of-contract rates until a resolution can be found, and a new contract is organised.

How long does it take to switch business energy?

There is a perception that switching your business energy is a long and drawn-out process and that any savings that can be made aren’t enough to make it worth the hassle. But the truth is that Bionic’s tech-enabled experts can find a better business energy deal within a matter of minutes, and switching with us could knock hundreds of pounds off the cost of your business energy bills.

The switch itself should only take five working days. Ofgem's Faster Switching scheme (see below) has dramatically cut the time it takes to switch from up to six weeks to just one working week.

But remember, you'll only be switched to your new business energy contract once your current contract has ended. This means if you secure new rates with six months left until your current contract end date, the switch won't actually take place for another six months.

Even so, arranging a new deal at the earliest opportunity makes sense. Customers who renew six months before their contract end date save up to 20% compared to customers who renew close to their contract end date.   

Switching times can be affected by the circumstances of your own business or an objection from your current supplier. These objections can happen for a number of different reasons, including:

• If you have an outstanding balance with your current supplier.
• If both your current and new suppliers agree that the switch request was made in error.
• If you have multiple meter points at one premises and fail to switch them all on the same day.
• If termination has not been given to your current supplier.
• If the incorrect contract start date has been given to your new supplier.

If your supplier blocks your switch, they have a legal obligation to let you know why they’re doing so, as soon as possible.

If you choose to switch and you experience switching times beyond six weeks, then you should write to your supplier and ask for a progress update.

Your supplier will have 14 days to respond to your query, and if they fail to respond within this time then you should seek to escalate the issue to your supplier’s CEO, who will have an additional 14 days.

If you’re having any issues with your business energy supplier or any aspect of your switch, our business energy experts might be able to help, so it’s worth giving us a call for some guidance. 

If your supplier does block your switch, and you feel the reason is not legal, then you should seek to raise the issue with the Energy Ombudsman. The Energy Ombudsman will review the reasons given by your current supplier for blocking the switch, and rule whether they are deemed legal or not before declaring a ruling for all parties.

The Energy Ombudsman is a type of free, independent dispute service for energy customers. You can usually take your complaint there if your supplier hasn't resolved it within eight weeks, or sooner if they send a deadlock letter.

You can contact the Energy Ombudsman in the following ways:

Phone - 0330 440 1624

Email - enquiries@os-energy.org

Website - https://www.energyombudsman.org/

Post - Energy Ombudsman, PO Box 966, Warrington, WA4 9DF

Remember, if you're not satisfied with the level of service that you receive from your supplier, then you should look to switch as soon as possible – and the fastest and simplest way to do so is with Bionic.

What is faster switching?

The rules on switching energy changed back in 2022. As part of Ofgem's 'Faster Switching' project, the time it takes to switch energy suppliers was cut from 18 days to just five. 

Faster Switching is an Ofgem initiative designed to make switching energy suppliers simpler and more cost-effective for homes and businesses. Switching energy suppliers should now take  5 working days, and the rules apply to both domestic and business energy switches.

• Domestic switches - The time the switch takes depends on whether you switch within your 14-day cooling-off period. If so, your switch will go through within five working days, but you'll still have time to cancel. If this is the case, you'll need to pay your supplier for the energy they supplied before you cancelled. Otherwise, your switch will take place within five days from when your cooling-off period ends.
• Commercial energy switches - With no cooling-off period on business energy contracts, the switch should take five working days from start to finish. If you choose a date for your switch outside of this five-day period (say your current deal doesn't end for a few months), your new provider will start supplying energy on your preferred date.

What if you’ve been switched to an energy tariff you didn't agree to?

Unlike domestic energy deals, commercial gas and electricity contracts don’t offer a cooling-off period - once you enter into a contract, you’re bound by its terms for the full duration outlined in the T&Cs. 

But if you’ve been switched to a new energy contract that you didn’t agree to, it is possible to break the terms of the contract early and transfer back to your old supplier.

If you think your business energy contract was switched without your consent, write to the new supplier as soon as possible and let them know your concerns. Keep written records of all correspondence over this matter, including dates, in case they are needed for evidence.

It’s also a good idea to write to your old supplier to tell them the situation. If the switch was made in error, your previous supplier may be able to support your case.

If you've been switched without your consent, the standard procedure is to revert you to your old supplier on their standard rate contract. 

If you've switched the wrong meter out of error, you can be transferred back to your previous meter, provided you have a contract in place with your current supplier. If not, your supplier may be unable to apply for the meter again.

If this is the case, then you will be reverted back to your old supplier on a deemed rate contract. If you are switched back to your old supplier but haven’t agreed on a formal contract with them, then you should look to switch to a better deal with better rates.

If your current supplier doesn’t acknowledge your initial correspondence within 14 days, then you should escalate the issue, in writing, to your supplier’s CEO. If you get no response after 14 days, you can escalate the issue to the Energy Ombudsman, who will independently investigate the issue and make a ruling.

It’s important to be aware that failing to organise a new contract when your current one expires can mean you're transferred onto a new contract, without formally agreeing to it. Fortunately, this is becoming less common, with many suppliers now choosing instead to transfer businesses onto a deemed rate 30-day rolling contract, which means you’re free to switch away with only 30 days’ notice.

How to change your business energy contract

Although you’re bound by the terms of your contract from the moment you sign it, there are certain circumstances that allow you to change certain aspects of your business energy contract.

• A change in circumstances - If the circumstances of your business have changed to the degree where your current contract is no longer feasible, such as a drastic decrease in your cash flow, then you should write to your supplier outlining the change in your circumstances. Remember to keep evidence of all correspondence with your supplier, along with the dates each was sent and any applicable evidence, for your own reference, if required.
• If you need to set up a repayment plan - If your business is in debt and it’s impacting your ability to pay for your energy, then you should write to your supplier and request a repayment plan. Repayment plans are designed to allow you to repay any arrears built up on your account while paying for additional energy you use. But before this can be offered as a solution, you must first provide your supplier with evidence that you are able to pay for the additional energy, while keeping up with the payments on your arrears.  Your supplier will refer to your previous payment history when deciding whether you are eligible for a repayment plan. If you have missed a number of past payments, then you are less likely to be offered a plan that allows you to use additional energy.
• If you’ve been moved to a deemed contract - If you’re looking to change the terms of your business energy contract because you noticed an increase in the amount that you’re paying, then it may be worth checking if you have been moved onto a deemed contract. If you are on deemed rates (also known as out-of-contract rates), your supplier may have increased your monthly direct debit amounts to reflect these new rates – but this can be corrected by giving monthly meter readings.

Remember that a deemed contract is used for businesses that have not agreed on a formal contract with a supplier. Typically, deemed contracts offer higher rates than the market average, so you want to switch away from these as soon as possible. Fortunately, you're not bound by the same rules when on a deemed contract, so you are able to switch to a new deal with only 30 days’ notice.

Ultimately, if you’re not happy with the terms of your current energy contract, and you are not in debt or struggling to keep up with payments, then it’s best to switch to a new energy deal as soon as your switching window opens.

Changing energy suppliers with Bionic 

Now you know the best time to switch business energy, the quickest and simplest way to change providers is to let Bionic’s tech-enabled team do the hard work.

One quick call to us is all it takes to have our experts search for the best deals from our panel of trusted suppliers and negotiate exclusive rates - saving you time and money that can be put back into your business.

To see how much you could save, put your postcode in the box on the right and start a comparison.

FAQs on the best time to switch business energy

Still unsure about when to switch business energy? Check out the answers to our most frequently asked questions:

When is the best time to switch business energy suppliers?

The best time is usually as soon as your switching window opens. That's often one to six months before your contract ends. Agreeing early lets you lock in a rate before prices move. Your new deal then starts the day your old one ends.

Can I switch business energy before my contract ends?

You can agree a new deal before your contract ends, but the switch only goes live on your end date. If you want to leave a fixed contract early, you may have to pay an exit fee. Check your contract's principal terms first.

How early can I renew my business energy contract? Many suppliers let you renew up to six months before your contract end date. Some windows are shorter, often around 90 days. Your supplier must tell you in writing when your window opens.

What happens if I don't renew my business energy contract?

You'll usually move onto out-of-contract rates, or sometimes a new fixed deal through automatic renewal. Out-of-contract rates are variable and usually much higher. You could switch away from them at any time.

How long does a business energy switch take?

The switch itself usually takes around five working days under Ofgem's Faster Switching rules. It could be quicker. If your current contract hasn't ended yet, the switch happens on your chosen start date instead.

Can my supplier stop me switching business energy?

Yes, but only for set reasons. These include unpaid debt, a fixed contract that hasn't ended, or errors in the switch request. Your supplier must tell you why it has objected.

Is there a cooling-off period for business energy contracts?

No. Business energy contracts don't have a cooling-off period, unlike household energy deals. The contract is binding once you agree to it. So you should consider reading the principal terms carefully before you sign.

Can I switch business energy if I've just moved premises?

Yes. When you move in, you'll usually be on deemed rates. You could switch away from deemed rates at any time without an exit fee. Comparing quotes early could save you from paying these higher rates for long.