Switching electricity supplier: what to compare before consenting

Neutral editorial AI illustration: a generic comparison table and a folder of contracts. This is not an actual supplier offer, a savings calculation or a particular customer's bill.

An offer to switch electricity supplier can look convincing: a large discount, a short description and a promise to handle everything. But a homeowner's decision concerns a specific contract, not an advertising phrase. For a comparison to be meaningful, you need to understand which terms are offered for your particular property, what information was used and what you retain before giving consent.

This article neither explains the lines of an electricity bill nor recommends a particular company. It describes preparation for a decision to change comercializadora: collecting comparable terms, clarifying open questions and recording the outcome. It provides no current tariffs, personalised calculation, guaranteed savings or claim that switching is always better than retaining the existing contract.

First, name the action precisely

CNMC distinguishes the distribution company connected with the network from the comercializadora with which the consumer chooses a supply contract. In its section on switching supplier, the regulator advises considering not just price but how it is revised, additional services and the previous contract's terms. It also presents an offer-comparison tool and information on tracking the switch. This brief account of those points does not replace checking a specific contract.

Do not confuse changing supplier with disconnecting supply, a new connection, changing the contract holder or changing capacity. Write down your objective: comparing terms for an existing property without other changes, or considering several actions separately. If another operation appears in the offer, clarify its basis and consequences before treating it as part of an ordinary switch.

An action concerning an existing home must relate to the correct contract and someone authorised to make the decision. Owning the apartment, paying individual bills and being a party to the contract are not always represented by the same record. Do not give consent for another person or assume a relative's assistance automatically authorises them to contract on someone else's behalf.

Record the starting situation without guessing the future

Gather the current terms and the data used for comparison. Keep a record of the period covered by consumption and how the home was used then. If the apartment stood empty for a long time but will now become a permanent home, past consumption is no promise of future usage. Where the scenario is unknown, acknowledge uncertainty rather than enter a convenient figure to produce an attractive difference.

Write a short note about your aim: understanding the pricing mechanism, removing an unclear additional service or comparing terms under a different pattern of occupation. This helps keep the task in view amid advertised benefits. Do not record desired savings as an expected outcome without a calculation using comparable conditions. Nor should you make technical changes to the installation merely to fit an appealing advertisement.

If the current contract involves the regulated market, social support or special circumstances, first clarify the consequences of switching through an official channel. Do not assume previous terms and benefits continue automatically. This article does not assess eligibility for support or recommend giving it up; uncertainty needs resolving before the decision, not after the first new debit.

Comparison starts with a common basis

For each offer, record the company name, precise product designation, date received and data underpinning the estimate. If offers use different consumption or periods, first bring the questions onto a common basis. You cannot fairly compare an estimate for occasional visits with one for permanent occupation and describe the difference as a tariff advantage.

The CNMC tool is a useful starting point, but viewing a result is not the same as concluding a contract and does not guarantee a future payment. Save the input data and date, then compare the selected option with the terms the company actually supplies for your consent. Do not claim the regulator personally checked an offer for your family simply because you found it through an official tool.

Avoid comparing one attractive line with another option's total. Ask which elements the estimate includes, which terms apply separately and what assumptions were used. If the answer remains incomplete, enter “not clarified” in your table, not zero. Missing information is not a free service.

Check what the discount and price changes mean

In an advertisement, establish what the discount applies to, how long it is described as lasting and what terms are offered after it ends. Do not invent what follows based on another contract. Ask for the relevant passage in the documents and retain it with the offer. An oral “it will be about the same afterwards” is not a verifiable answer.

Ask separate questions about the pricing mechanism: exactly what is fixed, what may change and how that is communicated. Do not treat the familiar word “fixed” as proof that every future payment will remain unchanged. You do not need to build a complex market model yourself; you need to avoid consenting to a mechanism you cannot yet explain in your own words.

If comparing scenarios, label them as scenarios. One might reflect previous use of the home and another an expected change. They help reveal how assumptions affect the decision, but do not predict weather, market prices or actual consumption. Do not select a convenient scenario merely to endorse an option you already favour.

List additional services separately

For your decision, separate supply from maintenance, assistance and other proposed extras. Clarify which you actually choose, how the documents describe them and what happens to them if the relationship changes again. Do not consider every service useful simply because it is called included: understand its content and terms first.

Previous additional arrangements also need checking. Do not assume every document relating to the home automatically ends when the supplier changes, or assert the opposite without reading the terms. Ask exactly which services the proposed switch concerns. The characteristics of a separate third-party contract cannot be established from the new supplier's general advertising promise.

If told of a possible payment for ending the previous relationship, ask for its basis and applicability to your case. Do not calculate a penalty from an old publication or accept any quoted amount as indisputably lawful. Retain the answer and, if needed, clarify it with the competent consumer-protection service. This article neither validates a specific penalty nor promises that costs can never arise.

Switching time: a right is not a promise of a particular day

The MITECO page read states a right to change electricity supplier within a maximum of ten working days from formalising the contract; exceptionally, complex work on site allows an extension of five working days. The ministry also states the right to obtain process-status information through the supplier and distributor. That is the source's precise context, not our guarantee of a date for a particular property.

The check also found another accessible CNMC page containing general information on electricity and gas which still states twenty-one days. This differs from CNMC's current specialised electricity section and MITECO's page. Do not therefore use the older general figure as a promised electricity-switching time. For your application, clarify the formalisation date, status and grounds for any departure through an official channel, retaining the answer.

Do not treat an automated acknowledgement of an application as confirmation that the switch is complete. In your home record, distinguish receipt of documents, giving consent and actual activation. If the wait lengthens or information conflicts, ask about the specific status rather than submitting several identical applications to different companies at random.

Before consenting, save a set of documents you can retrieve

Keep the offer, the supplied summary of terms, contractual documents and answers to material questions in one folder. Save the date and version, not just an advertising screenshot showing an amount. If a document changes after discussion, identify which version you are being asked to sign. Retain the old file for comparison rather than silently replacing it.

Read what an action in the selected channel actually confirms. Do not give a message code to an unknown intermediary merely because they promise to “check the offer”. Do not send your personal email or banking-account password to compare terms. Provide personal information only after checking the recipient, purpose and prescribed official contracting method.

If deciding remotely or by telephone, request available written material and clarify the applicable procedure for changing your decision. Do not automatically assume a universal ability to cancel any action at any time. Terms and circumstances need checking; this article does not determine an individual withdrawal period or replace a timely request for clarification.

After contracting, finish the check with facts

Keep the company's confirmations and record the actual switching date when it becomes known. Compare the first document after activation with the offer you accepted: does the product match, is there an unexpected additional service and is the link to your contract clear? This checks implementation of the decision, rather than re-examining every bill component.

If you find a discrepancy, describe the specific point and attach relevant material through a verified channel. Do not start with an unsubstantiated accusation or send your entire personal-document history when the question concerns one service. Record the enquiry number and response. Asking a question does not itself guarantee a refund or changed terms.

A good comparison lets you explain why a particular option was selected and which uncertainties remain. It need not result in switching: after examining the terms, someone may keep the current contract. In either case, the value is the same—an informed agreement to understandable terms instead of a promise of automatic benefit.

Sources and verification date

On 29 October 2026, we read CNMC — electricity retail and supply, sections on company roles and switching supplier; MITECO — switching supplier; to check the discrepancy — the general CNMC information page on switching electricity or gas supplier. Individual offers, personal data, applicability of penalties and savings for a particular home were not checked. The practical comparison framework is editorial, not personalised financial or legal advice.