Porto and Gondomar Swap Land Along a 34-Point Line, and 135 Homes Wake Up in a Different Municipality

A law published on Thursday redraws the boundary between Porto and Gondomar for the first time in living memory, and it took effect on Friday. Lei n.º 56/2026 replaces the old line with 34 surveyed points running from the Estrada da Circunvalação down to the bank of the River Douro. About 135 households and 16 commercial premises now sit in a different municipality from the one they sat in on Wednesday.

The law was approved by Parliament on 17 July, promulgated by President António José Martins Seguro on 12 August, countersigned by Prime Minister Luís Montenegro the same day, and published on 20 August in Diário da República (Official Gazette) n.º 161/2026, Série I. Its article 3 sets entry into force for the day after publication, which is Friday, 21 August.

Which parishes are involved

On the Gondomar side, three freguesias (civil parishes) are affected: Rio Tinto, the União das Freguesias de Fânzeres e São Pedro da Cova, and the União das Freguesias de Gondomar (São Cosme), Valbom e Jovim. On the Porto side, there is only one: Campanhã, the city's eastern parish.

Parliament legislated under article 161(c) of the Constitution, which reserves to the Assembleia da República the power to make laws on matters not assigned to the Government. Municipal and parish boundaries are one of them, which is why an adjustment negotiated between two town halls has to travel all the way to a presidential signature.

A line described street by street

The law itself is unusually concrete. Annex I lists 34 numbered points with metric coordinates, and each carries a plain-language description of where it physically sits. Point 1 is on the central reservation of the Estrada da Circunvalação (the EN 12 ring road) heading towards the IC29. Points 3 and 4 are the north and south sides of a roundabout on the same road. Points 7 and 8 are on and in the centre of the Nó das Areias interchange.

From there the line drops south through Rua das Águas Férreas de Campanhã, crosses a footpath and a garden wall, picks up the verges of Rua Oito de Setembro, runs along the axis of Travessa de Vila Verde, meets the EN 209, crosses open ground to Rua Dom António Ferreira Gomes, follows Rua do Freixo, joins the axis of the EN 108, and ends at point 34, on the kerb beside the Douro. Annex II carries the cartography. Several point descriptions note in passing that a street name is a Gondomar toponym, a small clue to how tangled the old boundary had become.

What moves in each direction

The published law states no areas at all: it fixes the line and leaves the arithmetic to the cadastre. The parcel figures reported when the two municipal executives voted in January 2025 were these.

Gondomar takes from Porto about 136,448 square metres at Areias, in Rio Tinto, and about 1,469 square metres of ground adjoining the Quinta de Villar d'Allen, in Valbom. That is roughly 137,900 square metres in total, and with it 67 homes and a single commercial or service premises.

Porto takes from Gondomar six separate parcels: about 38,733 square metres south of Areias; about 24,405 square metres north of the Circunvalação; about 91,005 square metres at Pêgo Negro; about 6,542 square metres south of Rua Oito de Setembro; about 4,310 square metres south of Granja, off the EN 209; and about 896 square metres south of the Villar d'Allen property. Those parcels come to roughly 165,900 square metres, and they bring with them 68 homes and 15 commercial or service premises. Figures circulated at the time varied; the law as published settles only the line.

Why it took eighteen years

The two councils first reached an understanding on new boundaries in 2012. Nothing came of it. Technical work restarted in 2018, and by early 2024 the municipalities had a proposed solution. Four parish assemblies then had to approve it: Fânzeres e São Pedro da Cova, Rio Tinto, the Gondomar, Valbom e Jovim union, and Campanhã. The two municipal executives voted in January 2025. Parliament passed the resulting bill in July 2026.

The stated rationale is not political but registral. The new line was drawn from the cadastral records the two councils had produced, so that properties already registered as belonging to one municipality would fall inside that municipality's administrative boundary. In other words, the map is being moved to match the paperwork rather than the other way round. That is why the point descriptions read like a surveyor's notebook, fixing the boundary to kerbs, verges, wall corners and road axes instead of to features that shift.

What actually changes for the people inside those parcels

A change of municipality is not cosmetic. It moves the property to a different council's Imposto Municipal sobre Imóveis (IMI) rate, since each câmara sets its own within a legal band, and it changes the municipal surcharge on company profits, the waste and water tariffs, the parish council that issues residence certificates, the school catchment, the licensing counter for building works, and the ballot the household votes on at local elections.

It does not, by itself, change the value on the property's tax record. The valor patrimonial tributário is set by the Tax Authority through a national formula, and readers can check theirs on their caderneta predial, the property tax record. What changes is the rate applied to it, and the identity of the body that collects. Our guide to paying IMI sets out how councils choose within the band and when the instalments fall.

What This Means for Expats

• If you own in eastern Campanhã or western Rio Tinto, check the map, not the postcode. The parcels are small and irregular, and the descriptions turn on which side of a verge or a wall you sit. Annex II of the law carries the cartography; the câmara municipal is the practical place to ask which side of the new line a specific article of property falls on.
• Your IMI bill is the first thing to look at. Porto and Gondomar do not levy at the same rate, and the change of municipality reaches the bill for the following tax year rather than mid-cycle. Do not assume the number that landed in May tells you anything about next year's.
• Update the address details that matter administratively. The street address does not change, but the freguesia and concelho on official records will for the affected properties. That matters for your atestado de residência, for school registration, and for anything that keys off the parish council rather than the street.
• Building and licensing files move counters. If you have a works licence, a short-term rental registration or a planning application in progress on an affected plot, the competent authority changes. Ask which office now holds the file before a deadline runs.
• This is a boundary correction, not a redevelopment signal. Nothing in the law rezones anything or grants any planning permission. Treat any estate-agent pitch built on the phrase "now in Porto" with the scepticism it deserves.

The eastern edge of Porto is already the busiest planning frontier in the city, with a new metro line to Gondomar working through its environmental study and large residential schemes moving through Campanhã. A tidy boundary makes those files easier to run, which is a large part of why two councils spent eighteen years on 34 points. It also quietly redistributes a small amount of tax base at a time when municipal surpluses are running on property-transfer and tourist taxes. For the 135 households involved, the practical work starts now, and it starts with reading a coordinate table.