Indexed vs fixed tariff: which one suits me in 2026?

What is a fixed tariff?

With a fixed-price tariff, you always pay the same price per kWh consumed, regardless of the time of day or the wholesale market price. It is the most predictable option: you know in advance how much you will pay for your electricity.

Advantages:

• Total predictability on your bill
• No surprises from market spikes
• Ideal if you cannot shift consumption to off-peak hours

Disadvantages:

• Generally more expensive than indexed (the retailer includes an “insurance” against rises)
• If the market drops, you still pay the same
• Usually come with a lock-in period (6–12 months)

What is an indexed tariff?

With an indexed tariff, the energy price varies every hour according to the wholesale market price (electricity pool). You pay the real market price plus a small margin from the retailer.

Advantages:

• Lower price on average (historically 10–20% less than fixed)
• Full transparency: you know exactly what you pay and why
• No lock-in period with most retailers
• Ability to optimise consumption based on hourly pricing

Disadvantages:

• Variability in your bill
• Requires some involvement to optimise schedules
• During energy crises, peaks can be very high

When does each one suit me?

A fixed tariff suits you if:

1. You value peace of mind above maximum savings
2. You cannot shift consumption to off-peak hours (work shifts, small children, etc.)
3. Your consumption is high during peak hours (10:00–14:00 and 18:00–22:00)
4. You don’t want to worry about checking hourly prices

An indexed tariff suits you if:

1. You can schedule appliances during cheap hours (washing machine, dishwasher, EV charging)
2. You have solar panels: during midday hours you produce more and draw less from the grid
3. You work from home and can adapt your schedule
4. Your main consumption is at night (off-peak: 00:00–08:00)
5. You want maximum transparency in pricing

The trick: simulation with real data

The best way to decide is to simulate both options with your real consumption data. At Smart Light that is exactly what we do: we calculate how much you would pay with each type of tariff using your actual (or estimated) consumption and current market prices.

Key fact: Over the last 12 months, an average Spanish household on an indexed tariff has paid 15% less than with an equivalent fixed tariff. But this varies depending on consumption profile.

Price breakdown: what do you really pay?

Your electricity bill has three main components:

Item	Approx. % of total	Description
Power charge	25–35%	What you pay for grid access (fixed)
Energy charge	40–55%	What you pay per kWh consumed (this is where fixed vs indexed matters)
Taxes and tolls	15–25%	VAT, electricity tax, meter rental

The difference between fixed and indexed only affects the energy charge. The power charge and taxes are virtually the same.

Our recommendation

For most households in 2026, an indexed tariff with no lock-in combined with some schedule flexibility is the most cost-effective option. But if your consumption is very rigid during peak hours, a competitive fixed tariff may give you more peace of mind without paying much more.

The ideal approach is to compare both options with your real data. Do it free on Smart Light →