Fixed or variable price: which electricity and gas deal should I choose, and when is switching worth it?
Fixed or variable electricity and gas prices: what each one buys you, how to compare two offers on the full yearly cost, and how to switch safely.
Photo: stephan de MARANTHI / Unsplash
After reading this article you will be able to:
- Compare a fixed and a variable offer on the yearly cost they set, fixed fee included, not on the price per kWh alone
- Read the boxes of the Italian Scheda sintetica, including the index, the spread and any early exit charge
- Switch supplier knowing whether a fee applies, how long it takes and how to undo a contract you did not want
On this page
Nobody can know in advance whether a fixed or a variable price will be cheaper over your contract, so the choice is between certainty and risk. A fixed price keeps the cost of each kilowatt-hour or cubic meter of gas the same for an agreed period, usually 12 months, and that certainty may cost more. A variable price follows the wholesale market plus a margin the supplier adds; in Italy the wholesale indices are the PUN for electricity and the PSV for gas, explained below. Switching is usually free and does not cut off your supply; the cost to check is a fee for leaving a fixed deal early.
All rules and figures were checked on 1 November 2026 on the official sources linked.
What exactly is a fixed price, and what is a variable one?
ARERA, the Italian energy regulator, defines both in its code of conduct for sellers (version in force from 1 November 2026, article 1). A fixed price is constant, or known in advance, for at least the first 12 months; it may cover the whole price you pay or only the part for buying the energy. A variable price changes automatically with the wholesale market or an index, by a formula in the contract; an offer fixed for less than 12 months and then variable counts as variable.
- PUN (prezzo unico nazionale) is the reference wholesale price of electricity on the Italian day-ahead market, where electricity for each hour of the next day is traded, calculated by GME, the energy market operator, as the PUN Index GME.
- PSV (punto di scambio virtuale) is the virtual trading point of the Italian gas grid, where wholesale gas changes hands; its price is the gas index. ARERA’s standard PLACET offers index gas to the monthly average day-ahead PSV price and electricity to the PUN.
- The spread is what a variable offer adds to the index, shown as “Indice + 0,00 €/kWh” with the seller’s figure.
Prices can move fast: ARERA raised the cost of buying electricity for its vulnerable customers by 63.4% from the third to the fourth quarter of 2026 (its typical customer’s whole bill rose 37.3%), as wholesale prices rose. A variable price passes on rises and falls; a fixed one does not. Every Italian fixed electricity offer must carry ARERA’s warning (article 20) that the fixed price “potrebbe risultare più basso o più elevato”, lower or higher, than a variable one.
How do you compare two offers properly?
The price per kWh, or per Smc (standard cubic meter, the unit of Italian gas bills), is only part of the bill. There is also the seller’s fixed fee, paid whatever you use (in Britain the standing charge, a fixed amount per day), plus network charges, system charges and taxes that are the same with every seller, as How to read your electricity bill shows. Two offers differ only in the price, or index plus spread, and the fixed fee.
Before you sign, an Italian seller must give you the Scheda sintetica, a standard summary sheet (ARERA), with these boxes (code, articles 17 to 21bis):
| Box | What to read |
|---|---|
| Spesa annua stimata | Estimated yearly cost before taxes at set levels: 1,500 to 3,200 kWh for a residence with 3 kW; 120 to 5,000 Smc of gas |
| Prezzo | Fixed or variable, and for how many months it is fixed |
| Corrispettivo per il consumo | Price per kWh or Smc; on a variable offer, the index plus the spread |
| Indice, Periodicità indice | Which index, how often it is updated, a chart of its past 12 months |
| Corrispettivo annuo | The seller’s fixed fee in euro a year |
| Modalità e oneri di recesso | How to leave, and any early exit charge |
Sellers compute that estimate with the method of ARERA’s free comparison site, the Portale Offerte, run by Acquirente Unico, which lists all retail offers; enter your yearly consumption and contracted power (the kW limit on your contract), or an offer code.
A worked example. Two hypothetical offers, seller’s part only.
| Assumption | Electricity | Gas | Source |
|---|---|---|---|
| Yearly consumption | 2,700 kWh | 1,000 Smc | example value, change it to yours |
| Average index over the year | €0.21 per kWh | €0.84 per Smc | starting point: ARERA’s PLACET index for September 2026, €0.2075 per kWh and €0.8432 per Smc; nobody knows the future average |
| Offer A, fixed for 12 months | €0.235 per kWh + €120 a year | €0.97 per Smc + €120 a year | example values, not market prices |
| Offer B, variable | index + €0.015 per kWh + €96 a year | index + €0.10 per Smc + €96 a year | example values |
| Offer A | about €750 | about €1,090 | 2,700 × 0.235 + 120; 1,000 × 0.97 + 120 |
| Offer B | about €700 | about €1,040 | 2,700 × 0.225 + 96; 1,000 × 0.94 + 96 |
Prices are before VAT, which adds the same percentage to both offers: with these numbers the variable offer saves about €50 a year on each supply.
How much it moves. The electricity offers cost the same if the index averages about €0.229 per kWh, 9% above the assumption; for gas, about €0.89 per Smc, 6% above. With the index 20% higher, offer B costs about €60 more than A on electricity and €110 more on gas; 20% lower, it saves about €160 and €220. ARERA’s 63.4% rise in one quarter was far larger than these swings.
What are the rules in your country?
Italy
- Regulated prices. Since 1 July 2024 the electricity Maggior Tutela, the service with conditions set by ARERA, is only for vulnerable customers: aged 75 or over, receiving the social bonus, with a disability under Law 104/92, among others (ARERA). The other households that had chosen nothing are in the Servizio a Tutele Graduali, a transition service with a seller chosen by auction in each area, until 31 March 2027, then move to a free-market offer of the same seller (the one with the lowest estimated yearly cost in December 2026), for at least 12 months with no early exit charge, unless they choose another. For gas, vulnerable customers can ask for the servizio di tutela della vulnerabilità, a monthly variable price based on the PSV.
- Switching is free, needs no new meter and does not interrupt supply. You sign with the new seller, which ends the old contract for you (delibera 302/2016, articles 3 and 6). Penalties and closing fees are banned, except on electricity contracts with a fixed price for a fixed period: there the seller may charge an early exit fee written in the contract you signed, as a maximum amount, proportionate and not above its direct loss. The fee lapses if the seller changes the conditions on its own.
- How long. Under the current process an electricity switch requested by the 10th of a month takes effect on the 1st of the next month; the last requests under it can be sent until 10 November 2026. From 1 December 2026 ARERA’s reform (delibera 58/2026) cuts the technical step to 24 hours, on any working day, for households whose supply is not suspended and who are not being charged for bills left unpaid with a previous seller; for the others it takes at least 10 working days. The legal limit of three weeks for the whole switch stays. A contract signed by phone, online or at your door is put into effect only after the withdrawal period (14 days, or 30 after an unsolicited home visit). If you ask, the seller can start the paperwork during that period, so the new supply may begin sooner, but not within it (code, article 9.5). Your supply codes stay the same: POD for electricity and PDR for gas, the codes on your bill that identify your connection point.
Great Britain
Ofgem’s price cap, which covers England, Scotland and Wales, limits the unit rate and standing charge of standard variable tariffs, not the total bill, and does not protect fixed tariffs; it is reset every three months. For 1 October to 31 December 2026 the Direct Debit average is 26.32p per kWh and 54.83p a day for electricity, 7.97p per kWh and 29.68p a day for gas: £1,723 a year at 2,500 kWh of electricity and 9,500 kWh of gas, with no VAT on electricity until 31 March 2027 and 5% on gas (Ofgem, 26 August 2026). Under the supply licence (condition 24, in Ofgem’s consolidated text to 1 August 2025) an exit fee is allowed only on fixed-term deals, must be proportionate, and does not apply from 49 days before the fixed term ends, or from the renewal notice if earlier. A switch takes up to 5 working days; you can cancel it within 14 days.
Germany
The Grundversorgung, the standard contract of the local default supplier, can be ended with two weeks’ notice; other contracts signed since 1 March 2022 run at most two years at first and can then be ended with one month’s notice, and switching must be free (Bundesnetzagentur). Since 1 January 2025 every supplier must offer a dynamic tariff to customers with a smart meter (§ 41a EnWG); suppliers with more than 200,000 customers must also offer a fixed-price contract of at least 12 months. The consumer body Verbraucherzentrale (29 July 2026) warns that many price guarantees leave out network charges, taxes and levies, up to 70% of the price.
Spain
The regulated PVPC, for individuals and micro-businesses up to 10 kW, has an energy price for each hour that mixes the daily and intraday markets (45%) with a basket of futures (55%) (Real Decreto 216/2014, articles 5, 6 and 9); free-market prices can be fixed. The regulator CNMC says switching is free, takes at most 21 days and is done by the new supplier; check the old contract for early cancellation clauses. Its comparison tool lists offers.
When is a fixed price worth it, and when a variable one?
- Fixed suits you if a stable bill matters more than a possible saving, as with a tight budget or a large winter gas bill. Check how long it lasts, what follows, and any exit fee; set a reminder to compare again before it ends.
- Variable suits you if you can absorb swings and want to follow falls without paying for a guarantee. A time-of-use tariff or a dynamic tariff helps only if you really shift consumption.
How do you switch safely?
- Take a recent bill: yearly consumption, contracted power, POD or PDR code.
- Compare on the Portale Offerte or your regulator’s tool; ask for the Scheda sintetica.
- Check your current contract for an early exit fee.
- Sign with the new seller only; it cancels the old contract for you.
- Keep the confirmation. In Italy a contract signed by phone, online or at your door can be cancelled at no cost within 14 days, or 30 after an unsolicited home visit (code, article 12.4); the EU’s Your Europe portal describes the same 14 days.
Phone and doorstep selling. In Italy a phone call alone does not bind you: you must sign the offer, or accept it in a form you can keep, such as an email, after receiving the written conditions (article 12.1bis). For a contract you never agreed to, complain in writing to that seller within 40 days of its first bill: under ARERA’s rules, sellers in the procedure can restore your previous supplier. ARERA’s consumer helpline, the Sportello per il Consumatore Energia e Ambiente, answers free on 800.166.654, Monday to Friday from 8:00 to 18:00.
Where does this answer stop?
Business supplies, solar homes and dynamic tariffs are not covered. Prices and rules change; this page is checked every month.
This page explains how it works and what to ask; it is not financial advice or a design. Electrical work and paperwork are for a qualified installer or advisor.
Where to go next
- How to read your electricity bill: the lines of the bill and your real price per kWh.
- Heat pump vs gas boiler calculator: what your prices mean for heating costs.
- Home energy: the complete guide: the other ways to spend less.
Common questions
Is a fixed or a variable price better for electricity and gas?
Neither is cheaper by rule. A fixed price buys certainty for the agreed period, which may cost more; a variable price follows the wholesale market, which can fall or rise sharply. ARERA makes Italian suppliers print the same warning on every fixed electricity offer: the fixed price may turn out lower or higher than a variable one. Choose fixed if a stable bill matters more to you than a possible saving.
How much does it cost to change electricity or gas supplier?
In Italy changing supplier is free for households, needs no new meter and does not interrupt supply; the new supplier handles it. ARERA's rules ban penalties and closing fees, with one exception: an electricity contract with a fixed price for a fixed period may carry an early exit charge, if the contract states it as a maximum amount and you approved it when signing. Spain's regulator also says switching is free; in Great Britain fixed deals may carry exit fees.
Can I change supplier before my contract ends?
Yes. In Italy any household can move to another offer at any time. If your current electricity contract has a fixed price for a fixed period, check its Scheda sintetica or contract for an early exit charge (onere di recesso anticipato): it must be a maximum amount you approved when signing. In Great Britain, a fixed deal may charge an exit fee, but none in the last 49 days before it ends.
How long does it take to switch electricity supplier in Italy?
Under the current process, an electricity switch requested by the 10th of a month takes effect on the 1st of the next month; the last requests under it can be sent until 10 November 2026. From 1 December 2026, ARERA's reform cuts the technical step to 24 hours on any working day for households whose supply is not suspended and who are not being charged for bills left unpaid with a previous seller; others wait at least 10 working days, within the legal limit of three weeks. A contract signed by phone, online or at your door is put into effect only after the withdrawal period, 14 days or 30 after an unsolicited home visit. Asking to start earlier can make it begin sooner, but not within that period.
Does the energy price cap affect fixed tariffs?
No. In Great Britain Ofgem's price cap limits the unit rate and standing charge of standard variable tariffs only; it does not protect a fixed tariff you agreed with your supplier, and it does not cap the total bill. For 1 October to 31 December 2026 the cap equals £1,723 a year for a typical household paying by Direct Debit.
Topics: comparison, energy prices, tariffs, switching supplier, ARERA, Italy