Fixed or variable price: choosing a business energy and gas contract

Fixed or variable is not a choice between "expensive" and "cheap": it is the choice of who bears the price risk, and it concerns only part of the bill. Network tariffs, general system charges and taxes follow public rules under any formula; the contract decides the supply cost.

ARERA's definitions

The Code of Commercial Conduct defines as fixed-price an offer in which the overall prices, or only the part relating to energy procurement, remain constant or in any case known for at least the first 12 months. An offer is variable-price when one or more components change automatically with wholesale prices or with an index defined in the contract, according to a formula with objective inputs and no discretion. Mixed structures — fixed for an initial period and then indexed, or fixed and variable combined — are classified as variable.

The reference indices

Current values are not reported in this article: ARERA publishes the indices used for PLACET offers every month, and market trends are on the Market indices page.

• PUN Index GME — since 1 January 2025 the old PUN has been phased out: zonal prices apply to demand and GME calculates the PUN Index GME, the average of zonal prices weighted by the quantities purchased in each zone. Since 1 October 2025 the time unit of the day-ahead market has been the quarter-hour.
• PSV — the Virtual Trading Point (Punto di Scambio Virtuale) of the national gas network: ARERA uses the monthly average of the day-ahead price at the PSV for variable-price PLACET offers.
• TTF — the Dutch hub to which ARERA indexed PLACET gas offers until 31 August 2023; a contract may still refer to it.

The typical formula is index plus spread: the spread is the part decided by the supplier, and it is the first term of comparison between offers linked to the same index. Updated values are on the market indices page.

What remains variable even in a "fixed" contract

• Network, charges and taxes — they are updated by the authorities and passed on to the bill, unless the offer has all-inclusive prices.
• Dispatching and capacity market — these are charges separate from the energy price, which electricity offers must state separately: check whether the contract locks them in or applies them at the value in force from time to time.
• Grid losses — the price may be expressed net or gross of losses: when comparing two offers the difference matters.
• After expiry — a switch from fixed to variable provided for in the contract is an "automatic evolution": for smaller supplies it must be communicated with at least 2 months' notice.

The rules for smaller supplies

For low-voltage customers and for gas up to 200,000 Smc a year, ARERA's rules on withdrawal (text valid from 17 July 2026) allow early withdrawal charges only in electricity contracts: fixed-price, fixed-term ones, and those of companies with more than 50 employees or over 10 million in turnover. The charges lapse if the seller unilaterally changes the conditions. In fixed-price, fixed-term electricity contracts, moreover, the seller cannot withdraw before expiry. At medium voltage and above the gas threshold only the contract applies.

For a business: what to check

• What is fixed — only the energy component, or dispatching and losses too? For how many months? What happens at expiry?
• Which index, exactly — PUN Index GME monthly average by band, hourly or quarter-hourly; day-ahead PSV or TTF; which calorific value is used to move from €/MWh to €/Smc.
• Volumes — look for clauses on deviations from expected consumption: shutdowns, new plants or a photovoltaic system change withdrawals.
• Exit and guarantees — withdrawal charges, notice periods, deposits or bank guarantees required.
• Budget — a fixed price gives a cost defined in advance, which in hindsight may turn out higher or lower than the indexed one. A middle path is to fix part of the volumes and leave the rest variable: the share is decided on the company's margins, not on market forecasts.

Ask the supplier for the formula written out in full, a worked example on a month already billed and the list of charges not included in the price.

Comparing formulas is part of the energy and gas contract optimisation service by IPGS ENERGY. Request a review.

Sources

• ARERA — Code of Commercial Conduct, text valid from 1 April 2026 (accessed 10 October 2026)
• ARERA — Withdrawal from supply contracts, text valid from 17 July 2026 (accessed 10 October 2026)
• ARERA — Standard offers for end customers, PLACET (accessed 10 October 2026)
• ARERA — Fact sheet 194/2024/R/eel, phase-out of the single national price (accessed 10 October 2026)
• ARERA — Resolution 388/2024/R/eel (accessed 10 October 2026)
• GSE — Technical rules on imbalance charges, February 2026 (accessed 10 October 2026)