Spain has set the seat allocation for the parliamentary election on 29 November 2026 The Boletín Oficial del Estado published the Real Decreto 806/2026 on 6 October, dissolving the Cortes and calling the snap election. Its annex lists the 350 seats in the Congreso de los Diputados by constituency: the Community of Madrid will have 38 MPs instead of 37, while the province of Cádiz will lose one seat, bringing its total to eight.
The allocation is governed by the Ley Orgánica 5/1985. Under this law, each province first receives two base seats; Ceuta and Melilla each receive one seat. The remaining seats are distributed among the provinces regularly according to population. The increase in the Comunidad de Madrid reflects the significant rise in its population since 2023. Cádiz is losing a seat at the same time because the total number of seats is fixed at 350; shifts in one region necessarily have consequences in another.
The decree starts the statutory deadlines in the election timetable, from the submission of lists to the financial audit of campaigns. As before, the actual allocation of seats to parties takes place separately in each constituency under proportional representation using the D’Hondt method. In large constituencies such as Madrid, additional seats can reduce the impact of thresholds and thus improve the chances of mid-sized lists. In smaller constituencies such as Cádiz, by contrast, losing a seat often benefits the largest parties, as competition for the final seats becomes more intense.
Analysts point out that the shift in Madrid and Cádiz may seem small overall, but could have national significance. The balance of power in the Congress of Deputies is determined by adding together many individual allocations across the provinces, some of them close. A reliable assessment of which party would win the additional seat in Madrid or miss out in Cádiz can only be made through an electoral simulation—and remains speculative until votes are cast on 29 November 2026. Recalculations based on the 2023 results illustrate possible allocations, but do not replace the new vote.
The legal and demographic basis of the current decision is not in dispute: the update to seat allocations follows the statutory system and the latest population data, with measurable consequences for the competitive conditions in Madrid, Cádiz and beyond.
Editor: Phillipe Schmidt-Araguin (Article created with AI assistance).