Galp's 2025-2026 Billing System Migration Leaves 2% of the Customer Book Unbilled Eight Months In — Households Receive €400-€800 Accumulated Bundles in May, DECO Reminds Clients of the Six-Month Prescription Rule and the Optional-Payment-Plan Right

Portuguese-resident electricity and natural-gas customers of Galp Power — the energy-supply arm of the Lisbon-listed integrated-energy group Galp Energia, SGPS — continue to receive accumulated backdated invoices in May 2026 following the customer-facing platform migration that the company executed across late 2025. The current operative position: roughly 2% of the customer book remains unbilled on the company's own read; affected households are now receiving bundled invoices that cover six-to-eight months of consumption and that land in the €400-€800 range on the median case, with outlier readings into four-digit territory for larger households or for those on combined electricity-and-gas dual-fuel contracts. The DECO Proteste consumer-defence body and the Entidade Reguladora dos Serviços Energéticos (ERSE) have both received dozens of complaints across the cycle; on Thursday 14 May, DECO escalated its public communication and reminded customers that the six-month prescription rule on unbilled consumption and the optional-payment-plan right both apply on the case-by-case dispute pathway.

The Backstory — The Late-2025 Billing-Platform Migration

In the final months of 2025, Galp executed an internal IT-stack migration to a new customer-facing electricity-and-gas billing platform — the new system carries the data on consumption-cycle readings, invoice generation, tariff-table application, the periodic-instalment cycle, and the consumer-portal interface. The migration was communicated to customers ahead of execution with a standard 'poderá haver alguma instabilidade no processo de faturação durante um determinado período' notification — there may be some instability in the billing process for a defined period — and with a 'possibilidade de fazer um faseamento do pagamento' mention — the option to phase the payment if invoices arrive late.

Eight months after the migration started, the operational read is that the instability period has run materially longer than the company-communicated window. The bulk of the customer book transitioned cleanly through the migration; a tail of around 2% of the customer book, on the company's most recent public statement to Jornal de Negócios, has been left in a partially-billed or unbilled state — the consumer-portal does not show recent invoices for the affected accounts, the bank-direct-debit (débito directo) cycle did not deduct the standard monthly amount, and the affected customers spent the winter heating-season cycle without seeing the actual cost-of-consumption land on their bank statements.

The May 2026 Bundling — €400-€800 Accumulated Invoices

The May 2026 reading: Galp is now catching up on the backlog. Affected customers are receiving bundled invoices in the post or in the consumer-portal that cover the entire unbilled period — typically six-to-eight months of accumulated electricity and gas consumption, totalled at the applicable Galp-Plano-Dinâmico or Galp-Combina tariff rates. The median case lands in the €400-€800 range. Outlier readings push into four-digit territory for larger households or for dual-fuel contracts that bundled both rails through the winter cycle. The complaints sent to DECO and ERSE on the cycle have documented cases as high as €800 across a single bundled invoice, with the underlying consumption profile being entirely standard — the figures are large because of the multi-month bundling, not because of any consumption anomaly.

The Six-Month Prescription Rule

DECO's central public-communication piece on the day reminds customers of the six-month prescription rule embedded in the consumer-protection framework on energy services. The rule, anchored on Article 10.º of the Lei dos Serviços Públicos Essenciais (Lei n.º 23/96, de 26 de julho) in its successively-amended form, sets a six-month prescription window for the supplier's right to bill: 'O direito ao recebimento do preço do serviço prestado prescreve no prazo de seis meses após a sua prestação' — the right to receive payment for a service provided prescribes within six months of its provision. The operational consequence for the Galp dispute: any consumption that occurred more than six months ago is, on the prescription-rule reading, no longer billable. If a customer in May 2026 receives a bundled invoice that covers consumption from October 2025, the October-2025 consumption is past the six-month window, and the customer can refuse to pay that portion in writing.

DECO's procedural advice on the prescription-invocation:

• Identify the prescribed portion: separate the consumption cycles in the bundled invoice. Any consumption-cycle reading older than six months from the invoice date falls inside the prescription window.
• File a written opposition: send a registered letter or a formal complaint through the company's customer-service channel that specifies the consumption-cycle readings being contested as prescribed.
• Pay the non-prescribed portion: the consumer remains liable for consumption that occurred within the six-month window; the dispute applies only to the older consumption.
• Keep the documentary chain: invoices, consumption-cycle readings, correspondence with the supplier — the documentary chain is the principal evidentiary base if the dispute escalates.

The Optional-Payment-Plan Right

The second leg of DECO's advice: Galp has proposed to affected customers 'planos de pagamento faseado' — phased payment plans — that spread the bundled-invoice amount across multiple months. Customers are not obligated to accept the company-proposed plan. The phased-payment-plan offer is a unilateral commercial proposal; the customer can reject it, negotiate a different schedule, or invoke the prescription rule first and then negotiate the payment terms on the non-prescribed residual.

The structural read: a payment plan that accepts the bundled invoice in full effectively waives the prescription-rule right on the older consumption. DECO's advice is to invoke the prescription rule first, and then negotiate the payment plan on the residual amount that falls inside the six-month window.

The ERSE Position — 2018 Recommendation on Billing-Delay Communication

The Entidade Reguladora dos Serviços Energéticos (ERSE) — the sector regulator — sits on the regulatory-oversight rail for the broader electricity-and-gas customer-relationship framework. ERSE has received dozens of complaints on the Galp billing cycle since late 2025 and continues to monitor the operational resolution path. The regulator's framework position rests on the 2018 ERSE recommendation on billing-delay communication, under which energy suppliers must: (i) inform the customer of the billing-delay situation through the customer's preferred-communication channel; (ii) publish the situation publicly on the company website; (iii) provide a clear estimate of when normal billing will resume; and (iv) offer phased-payment options on bundled invoices that follow.

The ERSE position on a regulatory-enforcement decision against Galp on the billing-cycle delay: the agency has not, on the public-information available on 14 May, opened a formal contraordenação process against the company. The supervisory cycle continues on the standard quarterly-reporting rail, and the regulator will continue to monitor the operational-resolution timeline through to the company's stated 'no próximo mês' normalisation window.

The Galp Position

Galp's public-communication position through the cycle: the migration was a one-time technical event, the bulk of the customer book transitioned cleanly, the residual 2% of unbilled accounts is in active operational-resolution, and the company expects to be fully caught up 'no próximo mês' — within the next month. The company has consistently offered phased-payment plans on the bundled invoices as the default contact-channel response to affected customers; the public-communication tone has been operational and apologetic rather than defensive.

The financial-reporting implication on the Galp Energia, SGPS side: the unbilled-customer backlog sits as a residual receivable-recognition item in the company's electricity-and-gas commercial-arm accounts. Galp Energia, SGPS reports earnings on a quarterly cycle; the Q1 2026 results, published in late-April, did not flag a material write-down on the unbilled-customer book, indicating the company's internal read is that the bulk of the backlog will be recovered on the catch-up cycle through Q2-and-Q3 2026.

The Consumer-Protection Framework Around This Case

The Galp billing-cycle dispute sits inside a broader Portuguese consumer-protection framework that has been incrementally tightened through 2024-2026. The principal frameworks the affected customer can invoke:

• Lei dos Serviços Públicos Essenciais (Lei n.º 23/96) — the foundational consumer-protection statute for essential public services (electricity, gas, water, telecoms, postal). Carries the six-month prescription rule, the dispute-resolution framework, and the right to file a complaint with the regulator.
• Livro de Reclamações — the consumer-complaints book, available both in physical form at the customer-service point and in electronic form on the livroreclamacoes.pt portal. A complaint filed via the Livro de Reclamações triggers a regulator-supervised response cycle. See our practical guide.
• DECO Proteste — the principal consumer-defence association, with a dispute-mediation arm and a public-information unit that issues the kind of advisory that informed the 14 May Galp coverage.
• ERSE — the energy-sector regulator, which carries the supervisory-and-enforcement framework on the commercial-relationship side of the electricity-and-gas markets.
• Centros de Arbitragem de Conflitos de Consumo — the network of regional arbitration centres that handle small-claims consumer disputes outside the judicial-court cycle.
• Judicial path — the standard small-claims and civil-court framework for the rare cases that don't resolve through the administrative-and-arbitration cycle.

What This Means for Foreign Residents

For foreign residents and entrepreneur-track residents on Galp electricity-and-gas contracts — particularly those who arrived in Portugal in the late-2025-and-early-2026 cycle and may not have noticed the absence of invoices through the winter heating season — the operative read on 14 May:

• Check your consumer-portal and bank-statement: log in to the Galp Pessoal customer portal (galp.com/pt/login) and verify whether your account has been billed normally through the November-2025-to-April-2026 cycle. Cross-check with your bank statement for the débito direto deductions on the expected monthly schedule.
• If you find a billing gap: contact Galp customer service to confirm the unbilled-cycle status. Ask for an estimate of the catch-up invoice amount and the expected delivery date.
• When the bundled invoice arrives: review carefully. Identify the consumption-cycle readings older than six months from the invoice date and prepare the prescription-rule objection in writing.
• Send a written objection by registered letter: the standard pathway is a carta registada com aviso de receção sent to the Galp customer-service address, with a clear statement of the consumption-cycle readings being contested as prescribed and a request for a revised invoice that excludes the prescribed amount. Keep a copy of the letter and the receipt.
• Do not accept a phased-payment plan without first invoking the prescription rule: accepting the bundled-invoice in full waives the prescription-rule right. Invoke the prescription rule first, get the invoice revised, and then negotiate the payment plan on the residual.
• Escalate to DECO and ERSE: if Galp's customer-service response does not resolve the dispute, file a complaint with DECO Proteste (via deco.proteste.pt) and a parallel complaint with ERSE (via erse.pt). Both bodies operate in Portuguese-language but accept English-language complaints on a best-effort basis.
• Consider switching supplier: the Portuguese energy retail market is competitive, with multiple alternatives to Galp on the electricity (Iberdrola, EDP Comercial, Endesa, Repsol, Goldenergy, Coopérnico, Lusenergia) and gas (Iberdrola, EDP Comercial, Galp, Floene) sides. The switching process is regulator-supervised and runs through the new supplier without active customer involvement on the technical side. See our utilities setup guide.
• Track your consumption-cycle readings independently: the smart-meter rollout under the Contador Inteligente framework has put most Portuguese households on a smart meter that reports consumption automatically; the consumer can also self-read the meter and submit the reading through the Galp portal to ensure billing accuracy.

The Broader Energy-Market Frame — Winter 2025-2026 Tariff Cycle

The Galp billing-cycle delay lands inside a winter heating-season cycle in which the Portuguese electricity-and-gas markets carried significant tariff-and-consumption-cost movement. The principal frames:

• Brent-and-Hormuz energy-price shock through Q1 2026: the Middle-East geopolitical tension pushed energy prices materially higher on the spot and forward-curve readings; the IPC energy index rose to 11.7% year-on-year in April 2026 (see our 13 May read).
• The cold-winter-cycle consumption profile: the storm-sequence from February to April 2026 pushed the average household electricity consumption profile materially higher than the 2024-2025 winter baseline; the bundled invoices that affected customers are now receiving reflect both the longer billing window and the higher per-cycle consumption.
• The ERSE-supervised tariff updates through 2025-2026: the regulated and free-market tariff curves were updated multiple times across the cycle. The bundled invoices that affected customers are now receiving will reflect the tariff-update profile that applied at each consumption-cycle date.
• The autoconsumo solar self-consumption framework: customers with a UPAC self-consumption installation may see a partially-offset bundled invoice. See our autoconsumo guide.

What's Next

The catch-up cycle is, on the Galp position, due to complete in June 2026. The DECO and ERSE complaint streams will continue to feed into the regulatory-supervision rail; the prospect of a formal contraordenação process against Galp depends on whether the company hits the stated June-2026 normalisation window and on the case-by-case dispute-resolution outcomes through the administrative-and-arbitration cycle. The Bank-of-Portugal-tracked consumer-protection framework, the DECO-tracked complaints volume, and the regulator-supervised commercial-relationship rail will all carry the residual operational tail of this case through Q2-and-Q3 2026.

For the affected foreign-resident customer base, the operative ask: check your account, prepare the prescription-rule objection in writing, do not pay a bundled invoice in full without first invoking the rule, and use the DECO-and-ERSE escalation channels if the customer-service rail does not resolve the dispute.

Source whitelist compliance: Galp Energia, SGPS institutional release and customer-communication channel — Tier 1, galp.com. Entidade Reguladora dos Serviços Energéticos (ERSE) — Tier 1, erse.pt — for the 2018 billing-delay-communication recommendation and the supervisory framework. DECO Proteste — Tier 2, deco.proteste.pt — for the consumer-protection advisory framework and the public-communication of 14 May. Diário da República — Tier 1, dre.pt — for the Lei dos Serviços Públicos Essenciais (Lei n.º 23/96) framework and the six-month prescription rule on Article 10.º. Observador (observador.pt), Jornal de Negócios (jornaldenegocios.pt), ECO (eco.sapo.pt), Folha Nacional (folhanacional.pt), Lusa (lusa.pt) — Tier 2 — for story discovery and corroboration of the 2% unbilled-customer-book reading, the €400-€800 bundled-invoice range and the company's stated June-2026 normalisation window. Portugal Post not consulted (blacklisted). On the household-electricity-contract side, our 2026 practical guide to setting up an electricity contract in Portugal — the MIBEL liberalised market, the ~30-comercializador retail landscape, the ERSE-regulated tariff framework, the potência contratada bracket choice, the Tarifa Simples vs Bi-Horária vs Tri-Horária decision, the Tarifa Social means-tested discount, the smart-meter rollout and the friction-free switching procedure that lets you change supplier without touching the wires sets the latest reference. On the natural-gas tariff side of the file, our 1 June read on ERSE's proposed 6.4% lift to the regulated TUR natural-gas tariff effective 1 October 2026 — couple-only households at €17.38 a month and two-child families at €32.53, the Tarifa Social keeping the 31.2% discount at €7.19 and €13.68 respectively, Mid-East supply disruption driving the third above-6% step in five years and the historical Galp-Nigeria take-or-pay legacy still shaping the regulated portfolio sets the latest reference.