Tariff stacking

Tariff stacking means using more than one payment or pricing arrangement at the same property. A home might buy electricity on a time-of-use tariff, receive a separate payment for exported solar and take part in a flexibility service. These layers can work together, but they do not automatically fit together.

There is no universal list of permitted household combinations. The answer comes from the rules for each scheme, the live terms of each contract and the way the meter or flexible device is registered. A combination that works with one supplier or battery may be blocked by another.

Treat the stack as separate layers

Start by writing down every arrangement that may affect the property:

1. Import supply: the tariff used for electricity bought from the grid.
2. Export payment: the contract used for metered electricity sent to the grid.
3. Flexibility or aggregation: payments for changing demand, generation or storage behaviour.
4. Device control: permission for a supplier, manufacturer or aggregator to schedule an EV charger, battery, heat pump or other asset.
5. Legacy support: any existing Feed-in Tariff (FIT) generation and export payments.

The first question is not whether all five exist. It is whether two contracts are trying to pay for, register or control the same action.

Import and export can be separate

Ofgem says a SEG licensee does not have to be the household’s electricity supplier. Electricity import, gas supply and SEG payments can therefore sit with different companies.

That does not mean every advertised export tariff is available alongside every import tariff. Suppliers may attach extra conditions to a particular product, such as taking import supply from them, using an eligible battery or having bought the installation through a specified route. A matched import-and-export tariff may also use one set of terms for both directions.

Check the actual product eligibility rather than assuming that Ofgem’s general freedom to choose a SEG licensee overrides a supplier’s conditions for a particular premium tariff. No current supplier rate is quoted here because rates and compatibility rules change frequently.

FIT generation and SEG export can coexist

A legacy FIT installation needs special treatment. Ofgem’s FIT guidance says an owner cannot receive FIT export and SEG export payments for the same installation and generation capacity. The owner must opt out of the FIT export payment before claiming SEG for that output.

The FIT generation payment is different. It can continue alongside SEG export payments. This is an important distinction: changing the export arrangement does not, by itself, require the owner to surrender the accredited installation’s generation payment.

Shared meters, extra non-FIT capacity and multiple installations make the position more complicated. Ofgem’s guidance includes separate rules for those cases, so the FIT licensee and proposed export supplier should confirm the treatment in writing before any change is made.

One asset cannot simply be enrolled twice

Flexibility services introduce another form of exclusivity. Under the Demand Flexibility Service (DFS) participation guidance effective in April 2026, a Unit Meter Point cannot be allocated to more than one registered DFS participant or DFS unit. A household should therefore not join the same national service through two providers and expect both to be paid for the same meter response.

This is not the same as saying that all flexibility stacking is prohibited. NESO’s April 2026 stacking list permits some combinations of DFS with other electricity-system services. Whether it allows jumping between services, splitting an asset’s capacity or delivering two services at once depends on the services and direction involved. Those are provider-level market rules, not permission to ignore a household contract.

The practical rule is simple: disclose every existing flexibility or managed-tariff arrangement to the proposed provider and ask it to confirm eligibility.

Read the device-control terms

A tariff may reserve control or demand-response rights over the connected asset even when the energy-supply and export contracts appear compatible. For example, as at 22 July 2026, Octopus’s smart-tariff terms for Intelligent Octopus Flux gave Octopus exclusive rights to use the customer’s low-carbon technology for demand-response services and prohibited entry into a third-party demand-response scheme while on the tariff.

This is a dated example, not a rule for every Octopus tariff or every supplier. The relevant live terms must be checked when a customer applies. Look for clauses covering:

• exclusive control or aggregation rights;
• third-party flexibility schemes;
• access to half-hourly meter and device data;
• which device, meter or whole premises the restriction covers;
• what happens if the integration stops working; and
• the supplier’s right to move the customer to another tariff.

Also check whether repeated cycling or remote control affects the equipment warranty. Contract compatibility and technical suitability are separate questions.

Compare the whole result

Do not choose a stack by adding headline rewards. Model the resulting energy flows and bill together:

net annual cost = import charges + standing charges + fees - export income - flexibility rewards

Use half-hourly import and export data where possible. A managed battery tariff can change when the home imports and exports, so it is unsafe to calculate the import saving and export income independently from the same unchanged historic profile. Allow for conversion losses, reserve settings, battery degradation and occasions when the asset is unavailable.

A lower export rate may be worthwhile if it unlocks much cheaper charging. A high export rate may be poor value if the qualifying tariff makes the home’s largest loads more expensive. The best combination depends on measured timing and volume, not the number of products in the stack.

Confirm the stack before switching

Tariff stacking depends on:

• whether import and export contracts can use different suppliers
• any requirement to place both contracts with the same supplier
• whether export payment covers solar generation only or also battery export
• the effect on any existing FIT export payment and continued FIT generation payments
• existing registration of the MPAN or asset with a flexibility provider
• exclusive control or demand-response rights granted by a contract
• supplier, aggregator, installer and manufacturer support for the device combination
• subscription fees, exit terms and minimum contract periods
• tariff behaviour after communications or device integration fails

Save the answers, tariff terms and eligibility confirmation with the system records. A supplier’s website can change after the contract begins, and the saved version shows what was agreed.

Related entries

• SEG
• Feed-in tariff (FIT)
• Demand Flexibility Service (DFS)
• Export tariffs
• Time-of-use tariffs
• Virtual power plant participation
• MPAN