Time-of-use vs. fixed tariffs: which is better for EV owners?
What are TOU and fixed tariffs?
A time-of-use (TOU) tariff charges different rates for electricity depending on the time of day. Typically, rates are lower during off-peak hours, such as overnight, and higher during peak hours when demand is greater. EV owners can therefore save by charging their vehicles during off-peak hours when electricity is cheaper.
A single-rate or fixed tariff charges a single rate for electricity at all times, regardless of when it’s used. This structure can provide stability for EV owners by offering predictable pricing throughout the day.
Fixed vs TOU tariffs: pros and cons for EV owners
When deciding between TOU and single-rate tariffs for your EV, you should consider the benefits and drawbacks of each option. Here's a breakdown of how they compare:
| Tariff | Pros | Cons |
|---|---|---|
| Time-of-use tariffs | Lower rates can offer significant savings during off-peak hours for charging your EV. | Higher rates during peak hours, which could increase electricity costs if you don’t manage your overall consumption well. |
| Encourages charging when grid demand is lower, supporting grid stability. | Risk of missing out on off-peak savings if you don't manage your charging habits well. | |
| Fixed tariffs | Simple, predictable pricing with the same rate at all times. | No opportunity to take advantage of cheaper off-peak rates. |
| No need to track off-peak hours, making it easy to manage costs and offering flexibility on when you charge. | You pay the same price regardless of when you charge, which may likely be higher than off-peak rates on a TOU tariff. |
How your charging habits influence the best choice
Your charging habits play a key role in deciding which tariff works best. TOU tariffs offer the most savings when you charge during off-peak hours - so the more you charge during these times, the more you can save.
Some EV owners charge at home overnight which suits a TOU tariff well as it allows them to take advantage of lower rates. Charging at work during the day may also align with off-peak times, depending on your location and TOU structure, so that’s something to check with your supplier.
If you’re a driver with an irregular schedule, or rely on public chargers, a fixed tariff might be better. With unpredictable charging times and public chargers, it can be harder to plan around specific off-peak windows.
Smart meters and compatibility
You’ll need a smart meter to access a TOU tariff, so before switching, check whether your home setup is compatible. You’ll definitely need to fit a smart meter if you don’t already have one, but you may also need to check that an older smart meter will work with your chosen supplier and the latest tariffs. If you’re unsure, check with your supplier.
How much could you save with TOU vs fixed?
The savings from switching to a time-of-use (TOU) tariff depend on when you charge your electric car. Charging overnight can be significantly cheaper, but electricity used outside discounted hours may cost more than on a standard single-rate tariff.
For example, here's how much it could cost to add 40 kWh of electricity to an EV using two TOU tariffs compared with a standard variable tariff. This shows that while you can save significantly on charging costs if you stick to the off-peak period, charging during the daytime costs more than charging on a single-rate standard variable tariff:
| Tariff | Off-peak rate | Day rate | 40 kWh off-peak | 40 kWh daytime |
|---|---|---|---|---|
| E.ON Next Drive Fixed V37 | 8.5p | 35.46p | £3.40 | £14.18 |
| Octopus Go Variable | 9.40p | 34.71p | £3.76 | £13.88 |
| Standard variable tariff (GB average) | 26.32p | 26.32p | £10.53 | £10.53 |
Illustrative rates for October 2026. TOU rates are for Eastern England; the standard variable rate is the Ofgem national average. Figures exclude standing charges and charging losses. Tariff rates vary by region and version.
Should you switch?
Wondering if it’s worth switching to a different type of tariff? TOU tariffs may suit you if:
- You charge regularly overnight or – depending on your tariff – during periods of low demand during the day
- You have flexibility around when you charge
- Your charging habits align with off-peak hours.
If you have an irregular schedule, rely on public chargers or need the simplicity of a set rate, then a single-rate tariff might be a better fit.
Before switching, monitor your overall energy usage with apps or tools from your supplier. This helps you understand your charging habits to determine whether a TOU tariff may offer savings.
Which suppliers offer both fixed and TOU tariffs?
Most major UK energy suppliers offer single-rate electricity tariffs alongside time-of-use (TOU) tariffs or discounted EV charging options, including:
Some offer cheaper electricity during fixed overnight periods, while others provide flexible smart-charging discounts. For example, OVO's Charge Anytime add-on allows eligible drivers to benefit from cheaper EV charging without a fixed off-peak window.
To find the best option, use our EV energy tariff comparison tool. Compare daytime and off-peak rates, standing charges and any eligibility requirements to find a tariff that suits your driving and household electricity needs.
How to switch between TOU tariff and fixed tariffs
Switching between time-of-use (TOU) and single-rate electricity tariffs is usually straightforward, whether you're staying with your existing supplier or moving to a new one.
- Compare tariffs: Check off-peak and daytime rates, standing charges and any exit fees before choosing a new tariff. Our tariff comparison tool makes this step easy.
- Request the switch: Contact your existing supplier or sign up with a new provider, which will handle the switching process on your behalf. Pick a tariff through our comparison tool, and we can handle the switch for you.
- Check your smart meter: Most TOU tariffs require a compatible smart meter capable of providing half-hourly electricity readings.
- Allow time for the change: Switching suppliers should take no more than five working days, although activating a TOU tariff may take longer if additional smart meter checks are needed.
Some suppliers make changing tariffs particularly easy. For example, Octopus Energy allows eligible customers to switch tariffs online, while E.ON Next can typically complete smart meter checks for existing customers within five days.
If you don't already have a compatible smart meter, your supplier may be able to arrange a free installation. However, this could delay the start of your new TOU tariff.
FAQs
Can I benefit from a TOU tariff without owning an EV?
Yes, you can benefit from a TOU tariff without owning an EV. These tariffs work for heat pumps, battery storage and large appliances too. Any household with the flexibility to use energy during off-peak hours can save by paying lower rates, cutting overall energy costs. Some tariffs also benefit households that own both an EV and a heat pump.
Do you need a smart meter for time-of-use tariffs?
Yes, you’ll need a smart meter capable of sending half-hourly meter readings to be able to switch to an EV TOU tariff.
Do TOU tariffs always save money vs fixed?
TOU tariffs save money only if you shift usage to off-peak times, meaning high peak-time use can offset any savings. It’s important to review your household habits and charging patterns to determine if a TOU tariff works for your energy needs.
Can I switch from a fixed to a time-of-use tariff if I rent?
You can usually switch to a TOU tariff if you rent, especially if you pay your energy bills to your supplier directly, but it’s still a good idea to get your landlord’s permission. If in doubt, check your tenancy agreement and ask your supplier about smart meter installation. Some suppliers may require meter upgrades, so confirm compatibility before making the switch.
