Energy tariffs explained: How to check when your contract is ending and due for renewal

Comparing business energy can take time you don't have. With so many suppliers offering different deals and rates, deciding on the best one for your small business can be a challenge. But first things first, how do you know when your current business energy tariff is ending? And what's the best way to then find your next deal? (spoiler: it's by letting Bionic do the hard work by comparing rates from a panel of suppliers all at once).

We've put together this guide to give you all the info you need to find out when your energy deal is ending and help make sure you're not hit with sky-high out-of-contract rates.  

Five-point summary of our guide to business energy tariff end dates and renewals

1. Your contract end date is one of the most important dates in your business diary — miss it and you could roll onto out-of-contract rates that are significantly more expensive than a negotiated fixed deal.
2. Most business energy suppliers require between 30 and 90 days' written notice before you can switch or renegotiate, and some larger contracts require up to six months. Checking your terms early is essential.
3. If your contract expires without a new deal in place, you'll be moved onto out-of-contract rates. These are often more expensive than the cheapest available tariffs, but you can usually switch to a fixed rate at any time.
4. There are a range of contract types available to suit different usage levels and patterns. It's important to pick the right type for you business as you can rarely exit a contract early.
5. The ideal time to start comparing new deals is when your renewal window opens, which can be up to six months before your contract ends. Bionic's Digital Renewal service does this automatically, so you never miss it.

What is an energy tariff? 

An energy tariff is what your energy provider uses to charge you for gas and electricity, both at home and in your business. The type of tariff you're on determines the rates you pay, along with any other fees, such as standing charges and VAT. 

Whether you’re a small startup or a large business with an established name, it’s good to shop around and compare energy providers when your existing tariff is up for renewal.  

By comparing energy deals, you’re ensuring you are on the correct tariff for your home and business needs. Plus, you know you aren't paying more than you should be because you’ve shopped around and seen what’s on offer.  

What are the different types of energy tariffs? 

With so many suppliers offering different tariffs and prices, it can be hard to know which will best suit your business.  

If you've ever run an energy comparison at home, you'll know there are two main types of tariffs - fixed-rate and variable-rate. But business energy comparison is different, and there are other options you'll need to consider based on the size of your business, along with how and when it uses energy.  

Below is a quick breakdown of the types of business energy deals on offer, along with some of the main pros and cons to help you decide on your next best deal. 

Fixed-rate tariffs

Fixed-rate tariffs charge a set price per unit kWh for the gas and electricity you use. The “fixed” term only refers to the unit rate and standing charge you’ll pay during your contract. This means your business energy bills will vary depending on your energy usage.

At Bionic, we work with a panel of trusted business energy suppliers that offer fixed-rate energy deals of between one and five years, depending on your circumstances.

Fixed-rate tariffs are great for businesses looking to take control of their bills and avoid price volatility. The thing to remember is that the unit rate and standing charge are fixed, but your bills will still vary depending on the amount of energy you use.

Pros: Fixed-rate tariffs are typically the cheapest option and can make budgeting for your business easier. They're also the only way to protect against future energy price rises. 

Cons: If energy prices fall, you could be paying more than the current market rate for your energy until your contract expires. Automatic rollover at the end of your contract means you'll pay more expensive out-of-contract rates, but you can solve this issue by signing up for a new deal before your current one ends. 

Variable-rate tariffs 

Variable-rate contracts are tied to market activity, so if market prices increase, you might pay more for each unit of energy your company uses. On the flip side, if prices drop, then you should pay less. If you’re willing to take the risk, you can just as easily reap the benefits if market prices fall. 

Pros: You could pay less for your energy if market prices drop. You can switch plans whenever you want.  

Cons: Prices generally tend to rise over time so your bills might increase even if you're using the same amount of energy. You’ll also have to constantly follow market prices to predict how much you’ll pay. 

Online energy tariffs

With an online energy tariff, you access and manage your account via the internet. You’ll be asked to send the meter readings to your supplier, and you’ll receive bills online via your account or email. You might also get a discount on your gas and electricity bill when you sign up to an online tariff.  

This means you won't get any paper bills through the post and will need to resolve any issues online (although a telephone number for energy supplier complaints should also be available). 

Pros: If you prefer to manage all of your bills and documents via the internet, this could be a good plan for your business. The discounted rates might also come in handy.

Cons: As all correspondence is managed online, you could overlook important information if your inbox is cluttered. You should be able to check your account details on your supplier's website regularly. If you prefer to have paper bills, then an online tariff may not be for you. 

Time-of-use tariffs 

Time-of-use tariffs — or “off-peak” tariffs as they’re sometimes known — charge less for energy usage through the night as people aren't using as much electricity. 

Economy 7 and Economy 10 are the two main types of time-of-use tariffs. These tariffs come with a smart meter that monitors how much energy you use during the day and night and gives you a price based on your consumption.  

Economy 7 

Economy 7 tariffs provide off-peak rates for seven hours of the night. You get charged more for any energy you use in the remaining 17 hours of the day. 

Economy 10 

Economy 10 tariffs give you off-peak electricity for 10 hours. The extra three hours will usually fall during quieter periods of the day. Depending on the supplier, Economy 10 runs in three separate intervals — an off-peak low rate in the afternoon, four hours in the evening, and three hours in the early morning. 

Pros: You can save money by using energy during cheaper, off-peak periods. It’s also a more sustainable option, as it helps balance demand on the grid.

Cons: Peak rates can be significantly higher, so you’ll need to carefully plan your energy usage to benefit.

Green energy tariffs

A green energy tariff means your electricity is matched to renewable sources — like wind or solar — through Renewable Energy Guarantees of Origin (REGOs) or Power Purchase Agreements (PPAs). Many suppliers now include green electricity as standard on fixed-term contracts.

Green tariffs are increasingly price-competitive with standard tariffs, making them a straightforward choice for businesses with sustainability goals or ESG reporting requirements. Switching to a green tariff can also reduce your Scope 2 carbon emissions — a factor that matters more and more to customers, investors, and supply chains.

Pass-through and flexible tariffs

Pass-through tariffs separate the wholesale energy cost from the non-commodity charges (such as network costs and policy levies), passing each through at actual cost. This can offer transparency and potential savings, but the bills are more complex to understand.

Flexible tariffs — typically available to larger commercial customers — let you purchase energy in tranches, taking advantage of price dips in the wholesale market. They require more active management and a good understanding of energy markets. For more detail, see Bionic's guide to large and industrial business energy.

At Bionic, we compare energy deals designed to meet the needs of your business, and can also offer blend and extend, flex approach, and pass-through tariffs. For more information on these types of tariffs and Bionic's bespoke procurement service, check out our guide on large and industrial business energy.

Deemed rates 

If you move into new premises without arranging a new deal or switching to a new supplier, you’ll be placed on a deemed rate tariff.  These are generally among a supplier's highest prices. If you find yourself rolled onto this type of plan, you can switch whenever you want.

Pros: You’ll still be covered on a plan if you forget to arrange a new deal or switch. You can switch to a different deal at any time.

Cons: Rates are usually more expensive than on a fixed contract, so it’s advisable to switch as soon as possible.  

Out-of-contract rates

If your current contract ends before you've arranged a new one or switched suppliers, you’ll be placed on out-of-contract rates.  These are generally among a supplier's highest prices. If you find yourself rolled onto this type of plan, you can switch whenever you want.

Pros: You’ll still be covered on a plan if you forget to arrange a new deal or switch. You can switch to a different deal at any time.

Cons: Rates are usually more expensive than on a fixed contract, so it’s advisable to switch as soon as possible.  

How to check when your business energy tariff is ending 

You’ll need to know the end date of your tariff so you can start shopping around in advance for alternative options to save money on your energy bills. Starting to compare early ensures you’re not paying over the odds if your tariff rolls over.  

If you're on a domestic energy deal, which you might be if you work or run your business from home, your supplier has a legal obligation to get in touch when your energy deal has between 49 and 42 days left to run. You can then switch at any time during this period without incurring an early exit fee (a one-off payment some suppliers make you pay if you want to end your deal early).  

But the rules are a bit different when it comes to business energy. If you're on a commercial energy contract, you need to wait for your switching window to open before you can start comparing different deals. This is usually between one and six months before your current contract's end date.  

Your supplier will get in touch to let you know that your switching window is open and will usually offer you a new deal.  If you find a contract with better rates during this window, you can sign up straight away (it sometimes pays to lock your rates in early to avoid future price rises), but the switch won't happen until your current deal ends.

If you don't sign up for a new deal and your current one expires, you'll be put onto your supplier's more expensive out-of-contract rates.  

If you don’t want to wait for your supplier to contact you, there are several easy ways to check when your tariff is ending yourself: 

• Check your latest bill — Along with your account name and number, the end date of your tariff should be displayed with all other important information. 
• Look at your switching letter — When it’s time for your tariff to end, you should receive a switching letter from your energy supplier. This will usually be delivered via post or electronically up to seven weeks before the end date of your contract. 
• Contact your energy supplier — If you’re struggling to find the date of when your tariff will end, then you can get in touch with your energy supplier directly. Make sure you have your account name and number to hand if you choose to phone them, as they’ll need this information to access your account.  
• Use Bionic's Digital Renewal service - When you switch energy with Bionic, you can sign up to our Digital Renewal service, so you never again need to worry about energy contract renewals. We'll proactively compare rates when your switching window opens and send you our best deals. You can then renew online to save time, money, and hassle.  

Understanding your renewal window and notice periods

Your renewal window is the period during which you're allowed to compare and switch to a new energy deal. For most business energy contracts, this opens between one and six months before your contract end date — but it varies by supplier and contract size.

You should also be aware of your supplier's required notice period. This is the minimum amount of notice you must give your supplier before the end of your contract if you want to switch or terminate. Miss this window and your contract may roll over automatically.

These are guidelines — your actual notice period will be stated in your contract. If you're unsure, contact your supplier or use an energy broker like Bionic to check on your behalf.

What happens when a fixed-rate energy tariff ends? 

What happens when your contract ends depends entirely on whether you've arranged a new deal.

• If you've signed a new contract - Your supply will transfer to your new deal from the date your current contract ends. No interruption to supply - the energy keeps flowing through the same pipes and wires.
• If you haven't signed a new contract - You'll be moved onto your supplier's out-of-contract rates. These are almost always significantly more expensive than a negotiated fixed deal.   

What happens if you don't act before your energy contract expires?

If you don’t renew or switch your energy contract before it ends, your supplier will automatically move you onto out-of-contract. These rates are almost always much higher than those on fixed-rate contracts and can cause your bills to increase sharply. For businesses, this could mean paying hundreds or even thousands of pounds more a year compared to a competitive fixed contract. You’ll remain on these costly rates until you arrange a new deal or switch suppliers.

What should you do if you've already been moved to out-of-contract rates?

If you discover your business has been switched to out-of-contract or deemed rates, act quickly, but don't panic. You can switch to a better deal at any time, since these contracts don't impose exit penalties.

1. Confirm there are no exit fees in your specific contract terms. Check how long you've been on the out-of-contract rates
2.  Use Bionic's comparison service to see what's available from across our panel of suppliers. Compare alternative fixed tariffs and switch

The longer you stay on out-of-contract rates, the more you pay. Even a few weeks on deemed rates can cost more than the hassle of switching is worth. Act immediately.

What happens to your energy tariff when you move business premises?

Moving to new premises adds a layer of complexity to your energy situation. Here's what you need to know.

• At your old premises - Give your current supplier as much notice as possible, ideally at least one month. Take a final meter reading on the day you move out and send it to your supplier so your final bill is accurate. Find out if your contract can be transferred to the new address or whether it needs to be closed and a new one started.
• At your new premises - When you arrive, the previous tenant's supplier will be providing energy. Take an opening meter reading immediately. Contact the existing supplier to register yourself as the new occupant. This helps prevent you from being billed for the previous tenant's usage.
• Arranging your new contract - You're not obliged to stay with the existing supplier. This is an ideal opportunity to compare the market and switch to a better deal. If you don't arrange a contract quickly, you'll be placed on deemed rates by the existing supplier, so act fast.
• Early exit and moving - Moving premises is one of the few situations where you may be able to exit a fixed-term business energy contract without paying the full exit fee. Check your contract terms, as most suppliers allow early termination on a change of tenancy.

Find out more in our guide to business relocation and change of tenancy.

Can your credit rating affect your ability to switch energy suppliers?

When switching business energy suppliers, your new supplier will typically carry out a credit check on your business. This is especially true for new businesses or those with limited trading history.

A lower credit rating doesn't necessarily mean you can't switch, but it can limit your options:

• Some suppliers won't accept businesses with low credit scores or no credit history.
• Others may accept you but charge an additional premium on your rates.
• Some may require a security deposit before you can take out a contract.
• Suppliers may insist on direct debit payment rather than quarterly invoicing.
• In some cases, a prepayment meter may be installed.

If your business has a limited credit history — for example, if you're a new start-up or have recently changed your company structure — it's worth knowing this before you compare deals. A broker like Bionic can advise on which suppliers are most likely to accept your business and on what terms.

Find out more in our guide to credit scores and business energy.

How to understand and choose the best energy tariff for your business 

When comparing energy tariffs, there are two main costs you should look for on your latest bill:

• Standing charge — This is the daily fixed cost included in your bill, and it’ll usually cover the maintenance of your meter. 
• Unit rate — This is the price that you pay per kilowatt-hour (kWh) for any energy that your business uses. You’ll want this figure to be as low as possible when you’re searching for deals.  

Don't forget that unit rates are only part of the picture. Non-commodity charges, including network costs like DUoS and TNUoS, and policy levies, can add 40–60% on top of your unit rate. When comparing contracts, make sure you're looking at total costs, not just the headline unit rate.

One other important point: business energy suppliers don't offer dual-fuel deals. Even if you arrange gas and electricity with the same supplier, you'll receive two separate contracts with separate end dates and notice periods. Make a note of both.

We can quickly find the best business gas and business electricity tariffs for your business in a matter of minutes. To get started, let us know your business name and postcode at Bionic.co.uk or click the Start a quote box on the right of this page.

When is the best time to look for a new energy deal?

The ideal time to start shopping for a new energy deal is as soon as your contract’s renewal window opens - this can be up to nine months before your current contract’s end date. 

Early comparison can give you more options and protect your business from price volatility. Set a calendar reminder for your renewal window or sign up for Bionic's Digital Renewal service, and we'll automatically find you our best renewal rates.

Can you switch before the contract's end date? 

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.

For more information, check out our guide to the best time to switch business energy suppliers.

How long will it take for a business energy switch to be completed? 

You can expect to wait anywhere between three and six weeks for a business energy switch to be completed, but you need to remember that your switch won't happen until your current contract has ended.

This means the length of time it takes to switch depends upon the length of your switching window and when you signed your new contract.

If, for instance, your switching window opens six months before your contract end date and you sign a deal on the first day of that window, then your switch will take six months. If you sign a new contract three months into your switching window, then your switch will take three months.         

Business energy deals don't have a cooling-off period, so make sure you're happy with the following before signing up for any deal:

• The length of the contract
• The notice period if you want to switch or end a contract
• The unit rates and standing charges

The rules are slightly different if you run a microbusiness, as you only need to give your supplier 30 days' notice before switching.

If you have a domestic energy deal, your switch should take no more than 21 days.

What to look for in a business energy contract before you sign

Business energy contracts don't include a cooling-off period, so it's essential to review the key terms before you commit. Here's what to check.

What happens if you can’t find a cheaper energy deal? 

If your previous tariff was already a good deal, you might struggle to find something cheaper than the deal you're already on, especially if you signed up for a three-year or five-year fixed-rate deal. This is because energy prices are likely to have increased quite significantly during this time. 

But that doesn't mean you shouldn't switch. Signing up for a fixed-rate deal to run from when your current one ends means you won't be rolled onto expensive out-of-contract rates. You should also be able to negotiate better rates with your new or existing supplier. 

Get in touch with the team at Bionic today to find a deal that can suit your business.  

How to prevent a contract from automatically renewing

To avoid automatic renewal, check your contract’s terms and make a note of your end date and the supplier’s required notice period. This is typically between 30 and 90 days before expiry. 

When your contract enters its renewal window, run an energy price comparison and sign a new fixed rate contract with a new supplier or your current supplier. This will begin when your current contract ends, and you won't automatically be renewed on your supplier's more expensive out-of-contract rates.

Micro businesses have some regulatory protections, including clearer renewal notifications and more flexible switching rules. Find out more in our guide - How does being a micro business affect your energy contract?

Signing up for Digital Renewals with Bionic will guarantee you never miss a renewal. Be proactive to make sure you’re never locked into a costly renewal by accident.

What to do when moved to out-of-contract rates

If you discover your business has been switched to out-of-contract rates, act quickly. You can switch to a better deal or supplier at any time, as these contracts don’t tie you in. 

Compare alternative fixed tariffs using Bionic’s service and arrange to switch to a contract that meets your needs. The longer you remain on deemed rates, the more you’ll pay, so prompt action helps keep energy costs under control

How to switch energy tariffs with Bionic 

Comparing and switching energy tariffs may seem overwhelming, but the tech-enabled team at Bionic do the hard work for you.  

No matter which tariff you choose, you’ll need to make sure it can withstand all your business needs. Knowing when your tariff ends and how to switch contracts can be a great way to save your business time, money, and keep it moving forward.  

Keeping up with the latest and best deals needn’t be a challenge. At Bionic, we’ll compare over 20 trusted UK business energy suppliers, then talk you through the quotes that you see on screen to make sure that you’re always getting the best price. Get in touch with the team today and switch your energy tariff.  

We can also sort other business essentials, including insurance, phone and broadband, and business loans. 

Frequently asked questions about business energy tariff end dates

Still unsure about the end date on your energy contract and what you need to do next? Check out the answers to our FAQs.

How much notice should a business give before its energy contract ends? 

Most business energy suppliers require between 30 and 90 days' written notice before your contract end date if you want to switch or renegotiate. Some larger commercial contracts may require up to six months' notice, so checking your contract terms early is essential. Missing the notice window can lock you into an automatic rollover at significantly higher out-of-contract rates.

What happens if you miss the renewal window on a business energy contract?

If you don't act before your contract expires, most suppliers will roll you onto out-of-contract rates. These are typically much higher than your contracted unit rate and can cost a business considerably more over time. The moment you realise you've rolled over, it's worth contacting a broker immediately - you can usually switch to a new fixed deal within a few weeks.

Can a business switch energy supplier mid-contract?

It's not usually possible to exit a business energy contract early. The way non-domestic energy contracts are structured means most fixed-term contracts lock you in for the duration. If your supplier has materially changed the terms of your contract, this may give you the right to exit without penalty. The same may apply if you cease trading or you have a change of tenancy.

How long does it take to switch business energy suppliers?

Switching business energy supplier typically takes between two and six weeks from the point of signing a new contract, though the process can be faster or slower depending on your meter type and outgoing supplier. If you're under contract, your new one won't start until your current one ends. It's important to factor this in when planning your renewal. To give you the most flexibility and avoid price volatility, it often makes sense to start the process at least three months before your end date.

Does a business energy contract automatically renew?

Yes, most business energy contracts include an automatic rollover clause, meaning that if you don't actively switch or renegotiate before the end of your contract term, your supply will continue at the supplier's out-of-contract rates. These are almost always higher than your previous contracted rate. Setting a calendar reminder for your renewal window is one of the simplest ways to avoid this. Or using Bionic's Digital Renewals means you'll never miss another renewal - we do all the work for you.

Can you have separate end dates for gas and electricity contracts?

Yes. Business gas and electricity contracts are separate agreements and can have different end dates, even if you're with the same supplier for both. Your contracts may even be with different suppliers and have different notice periods. This is why it's important to track both independently. Aligning your renewal dates when you next switch can simplify future contract management and may give you more negotiating leverage if you're comparing dual-fuel-style deals.

Does the size of a business affect when and how it can switch energy tariffs?

Business size can affect the switching process - microbusinesses have stronger regulatory protections, including shorter notice periods and the right to exit rollover contracts more quickly, while larger commercial customers are subject to purely contractual terms with fewer automatic protections. If you're unsure which category your business falls into, an energy broker can clarify your rights and the options available to you before your contract ends.