When is the best time to switch business energy?

The short answer

For most small businesses the best time to switch is shortly before your current fixed contract ends. Leave it too late and you may roll onto a higher rate. Leave it too early and you may owe a termination fee. Business energy is not covered by the household price cap, so there is no safety net if you slip onto an expensive rate.

Step one: find your contract end date

Look in these places, in this order:

• Your contract or Principal Terms. The end date, length and any termination fee should be stated there.
• Renewal letters or emails. Citizens Advice says a supplier should contact you about three months before a fixed term ends to explain your options. If yours did not, you can complain.
• Your online account or a recent bill. Some bills show the contract end date.
• Your broker. If you used one, ask for the end date in writing.

Still stuck? Ring the supplier and ask for it in writing. Our guide on how to find your business energy contract end date goes through every route.

Step two: understand what happens at the end

When a fixed term finishes, one of three things happens:

1. You agree a new contract with your current supplier or a different one.
2. You are rolled over onto a new fixed term, if your contract allows it and the supplier has followed the renewal-information rules. A rollover cannot be longer than 12 months. See rollover contracts.
3. You move onto an out-of-contract rate if there is no rollover, or it has run out. These rates are usually the most expensive, but you can leave without a termination fee.

Evergreen contracts, which have no end date, are different: the supplier can ask for up to 30 days' notice from you. The details are in our evergreen contract entry.

What the notice rules say

Since 1 October 2022, suppliers cannot require a microbusiness to give notice to leave or switch, except under an evergreen contract (up to 30 days). Out-of-contract customers cannot be charged a termination fee. Older contracts often had notice windows of their own (Ofgem cut the longest notice a supplier could require from a microbusiness from 90 days to 30 days in April 2015). If you signed a contract before October 2022 and it is still running, read its wording rather than assuming the current rules describe it.

If you are not a microbusiness (see what counts as a microbusiness), some of these protections may not apply to you. Read your own contract before relying on this page.

Official guidance says the same about getting out early: switching before a fixed term ends may trigger an early termination fee. Check the figure in your contract before you decide.

How early can you line up a new deal?

You can usually start comparing and agreeing a deal while your current contract is still running, with the new supply starting on the end date. Citizens Advice notes you can ask your new supplier to switch on a specific date, such as the day your fixed term ends. How far ahead a supplier will fix a price is up to each supplier; British Gas, for example, says on its renewal page that you can ask for a renewal quote up to 12 months before your end date. Others may offer less, so ask. Our page on how early you can agree a new energy contract covers it in more detail.

Switching itself is quick: Citizens Advice says to expect the change within five working days. In practice, build in extra time for gathering details and checking quotes. Our guide on how long it takes to switch explains the steps.

What waiting too long costs

Moneysupermarket Business published average rates for October 2026 (21 October 2026). It put the average out-of-contract electricity rate at 40.0p/kWh, against 28.4p/kWh for an average microbusiness fixed rate. Gas was 12.0p/kWh out of contract against 8.8p/kWh fixed. These are indicative averages from a comparison site, not offers.

Worked example

A small shop uses 20,000 kWh of electricity a year, or roughly 1,667 kWh a month. Using the unit-rate gap only:

• Gap = 40.0p − 28.4p = 11.6p per kWh.
• Per year: 20,000 × £0.116 = £2,320.
• Per month: £2,320 ÷ 12 = about £193.

So every month you drift past your end date at these average rates could cost roughly £193 more in unit charges alone, before standing charges, the Climate Change Levy and VAT. Use our out-of-contract energy cost calculator with your own numbers.

Is there a "best month" to buy?

Many owners ask whether winter or summer prices are better. Wholesale prices move for many reasons, and nobody can reliably call the bottom. A sensible approach is to treat your end date as the deadline and compare quotes in the weeks beforehand, instead of waiting for a market dip that may not come. Price forecasts are often wrong, so do not base your timing on them.

One timing point that does matter: when you move premises or take over a site, you can be put on a deemed rate until you choose a contract. Our guide to moving premises and deemed contracts covers that case, and it is also a good moment to switch.

If gas and electricity end on different dates

Many businesses have two contracts that expire months apart. Each fuel is a separate supply with its own MPAN or MPRN, and you can switch each one separately. If the dates are far apart, the sensible plan is to diarise both, and treat the earlier one as the first deadline. When you next renew, you may choose to align them so there is one date to remember.

If your business is seasonal or may close

A holiday let, a seasonal café or a business you plan to sell has a different risk: being locked into a long term you cannot use. Ask about moving a contract to new premises and what happens on a sale before you choose a long term.

A simple diary routine

• Six months before the end date: note your usage and gather your MPAN, MPRN and meter readings.
• Three months before: expect the supplier's renewal information. Start comparing quotes. See what you need for a quote.
• One month before: have your new deal agreed with a start date matching the end date.
• On the date: take meter readings and send them to both suppliers.

Put the end date in two calendars, yours and a colleague's. A missed renewal is the commonest and most expensive mistake in small-business energy.

Next steps

1. Find your end date today and put it in your diary.
2. Check your contract for termination fees and rollover wording.
3. Start comparing about three months out.
4. Agree a start date that matches your end date.

Ready to move? Our how to switch business energy guide walks through the process.