Supplier exit and switching for time-of-use tariffs

Exit terms, meter data, device eligibility and export-contract checks when leaving or joining time-of-use tariffs.

Leaving or joining a time-of-use tariff uses the ordinary supplier-switching process, but the tariff adds dependencies that a single-rate account may not have. Half-hourly meter data, device compatibility, import-and-export links and supplier control permissions can all affect the result.

The safe approach is to treat four changes separately:

the legal electricity supplier
the import tariff
the export contract
any EV, battery or heat-pump control service

They may be sold under one brand, but they do not necessarily start or end together.

Read the actual exit terms

“Time of use” describes the pricing structure, not whether the tariff is fixed or variable. One time-of-use tariff can have a fixed term and exit fee; another can be left without charge.

Check the tariff information and accepted terms for:

contract end date
exit fee per fuel or account
whether a tariff change within the same supplier also triggers the fee
notice or processing period
what tariff applies while a device check or meter-data setup is incomplete
any wait before the customer can rejoin

For domestic fixed-term supply contracts, Citizens Advice explains that a supplier cannot charge an exit fee where 49 days or less remain. Earlier in the term, the contract may permit one. Compare the fee with the saving over the remaining period rather than treating either as decisive on its own.

Do not copy an exit-fee table from a comparison article. Suppliers issue new tariff versions with different fees, and a customer already on an older version keeps the terms of that version.

A rejoin restriction is not an exit fee

A tariff can be free to leave but still restrict a return. These are different costs.

For example, Octopus’s smart-import terms state that a customer who switches away from a smart import tariff cannot switch back to a smart import tariff within 30 days. Tracker also has a longer tariff-specific rejoin restriction in its own terms.

Those points are current as at 22 July 2026 and concern Octopus products, not a market-wide Ofgem rule. Other suppliers may use different eligibility or rejoin conditions. Check the current wording before planning seasonal or short-term tariff changes.

Customer-service reports about whether a supplier sometimes overrides a wait are not a dependable rule. Plan against the contract unless the supplier confirms an exception in writing.

Confirm the meter can support the new tariff

A half-hourly tariff needs usable interval data. A smart meter being present on the wall does not by itself prove that the new supplier can retrieve the data needed for billing.

Before switching, confirm:

meter type and serial number
import MPAN and current registers
whether the meter is enrolled in the national smart network
whether half-hourly consent is recorded
whether recent interval data are complete
how the new supplier bills missing data
whether a meter exchange or reconfiguration is required

Second-generation smart meters are designed to retain smart operation through a supplier switch using the Data Communications Company network. First-generation meters enrolled into that network should also be interoperable. An unenrolled or communications-fault meter may continue measuring accurately while automatic readings or smart-tariff access are interrupted.

Do not assume the new time-of-use tariff begins on the day the legal supply switches. Some products require the account to land first, then verify the meter or device before the specialist tariff is activated. Obtain the effective tariff date in writing and check the first bill.

Save interval data before leaving

Supplier apps and portals often provide the easiest access to historic half-hourly data. That access can disappear after the account closes even though the supplier retains records for billing and legal purposes.

Before switching, download:

import interval data
export interval data
bills and statements
tariff terms and prices
device schedules and charging history if relevant
photographs of all meter registers on the changeover date

These records let the customer verify final and opening bills and compare the new tariff with what would actually have happened on the old one.

Third-party energy apps can be useful archives, but the supplier’s own meter data and bill remain the starting point for a billing complaint.

Device-managed tariffs need a second compatibility check

Some tariffs merely apply cheap rates during fixed hours. Others integrate with an EV, charger, battery or heat-pump control platform.

For a managed tariff, confirm:

supported device and firmware version
app account and internet requirements
whether control is through the vehicle, charger or another gateway
minimum use or fair-use conditions
the tariff treatment when the integration fails
whether the supplier receives exclusive flexibility rights
what happens to stored schedules when the tariff ends

A device that qualified when the customer first joined may leave a supplier’s supported list later, or a replacement vehicle or charger may not qualify. Leaving on the assumption that the same product will still be available on return creates avoidable risk.

Remove supplier control permissions after the old service ends, but only when the final schedule and billing period are clear. Then authorise the new provider and confirm that manual charging or heating controls still work during the handover.

Import and export can move separately

The SEG (Smart Export Guarantee) does not require the import and export supplier to be the same company. Each side has its own MPAN and contract.

Commercial tariffs can nevertheless link them. A premium export rate may require:

an import tariff with the same supplier
a particular compatible import tariff
equipment installed by that supplier or partner
continued device control

Changing import can therefore end access to the premium export rate even where the export MPAN has not yet transferred. Read the export contract’s eligibility and termination clauses before starting the import switch.

Ask both suppliers to confirm:

the old export tariff’s final eligibility date
whether it falls to another rate or ends entirely
when the new export contract can be applied for
whether the import account must be live first
the required opening and closing export readings
the new payment start date and any backdating rule

There is no universal six-week gap and no scheme-wide backdating promise. Export can remain with the old supplier if the tariff permits export-only customers, or it may need a separate switch. The correct sequence depends on both contracts.

Internal tariff change versus supplier switch

An internal tariff change leaves the legal supplier and MPAN registration in place. That can reduce administration, but it does not guarantee an instant change. Meter checks, device authorisation, cooling-off rules or product queues can still apply.

A supplier switch changes the licensed retail counterparty. The new supplier coordinates the transfer, while a separate export or managed-device arrangement may follow its own process.

In either case, record the requested and confirmed effective dates. If the account shows a standard or default tariff during the gap, establish whether that is an agreed interim step or an error before allowing automation to run against assumed time-of-use prices.

Calculate the true switching cost

Include more than the import-rate difference:

switching value = import saving + export change + service incentives − exit fees − transition costs

Transition costs can include:

days billed on an interim tariff
lost premium export eligibility
missed battery or EV optimisation
a paid device subscription
the value of a reward that is forfeited

Use dated, written terms for every component. Anecdotal processing times and screenshots of somebody else’s tariff are not reliable inputs.

On the changeover

Take meter readings and photographs, then check:

The old tariff ended on the agreed date.
The new supplier used the same opening reading as the old supplier’s closing reading.
The correct time bands and standing charge appear on the first bill.
Half-hourly import and export data continue without unexplained gaps.
EV, battery or heat-pump schedules use the new tariff times.
The export payer and rate remain what was agreed.

Use the supplier’s complaint process promptly if the switch is delayed or erroneous. Ofgem sets automatic-compensation rules for specified switching failures; the live Ofgem page should be used for the current amounts and deadlines.

If the supplier fails instead

A failed supplier is different from a voluntary switch. Ofgem appoints a replacement and continuity of supply is protected, but the specialist time-of-use, export or device-control product is not guaranteed to continue on identical terms.

Preserve meter and tariff evidence, wait for the appointed supplier’s account instructions, then reassess automation and export once the new contract is known. A battery should fall back to a safe local schedule rather than continue trading against prices it no longer receives.