SRU law in Paris: who is behind, who pays, who pools

Adopted on 13 December 2000 and tightened several times since, the Solidarité et Renouvellement Urbains (SRU) law is one of the texts most continuously present in the public debate on housing. It requires every municipality of more than 3,500 inhabitants located in a high-pressure zone (Île-de-France and major urban areas) to have a minimum threshold of 25% social housing in the main residential stock. In Paris, this threshold is reached at the municipal level (~25%), but eight arrondissements are below the threshold, and the law's penalty mechanism applies — with a little-known Paris peculiarity.

This article explains the text, the thresholds, the calculation of penalties, the internal pooling allowed in Paris, and the prefectoral deficiency procedure that sanctions the most serious delays. It complements our analysis of the geography of Paris social housing on the legal side.

The founding text, and its successive tightenings

The original law of 13 December 2000 (SRU law stricto sensu) inscribes in the Construction and Housing Code, articles L.302-5 to L.302-9-2, the obligation for affected municipalities to reach 20% social housing by 2020. Three laws have progressively tightened this base:

1. MOLLE law of 2009 (Mobilization for housing and the fight against exclusion): strengthening of sanctions for deficient municipalities
2. ALUR law / Duflot II law of 2013: threshold raised to 25% in the highest-pressure zones (including Paris), deadline pushed to 2025, penalty cap doubled
3. Equality and Citizenship law of 2017: tightening of the deficiency procedure and improved traceability of spending by deficient municipalities

For Paris, which is in Île-de-France, the 25% threshold with a 2025 deadline therefore applies today — with a triennial schedule of intermediate reviews.

Three thresholds not to confuse

The SRU threshold is not unique. Three levels coexist:

• 25% in most high-pressure zones (Île-de-France, Paris/Lyon/Mediterranean urban areas)
• 20% in less high-pressure zones (where the mixity goal remains valid but the required effort is lower)
• Exemption or modulation for certain municipalities (low population, strong geographic constraints, low employment basin)

In Paris, it is 25% without exception. The calculation is performed on main residences in the stock, based on the SRU inventory published annually by the DRIHL (Direction régionale et interdépartementale de l'hébergement et du logement). It is this inventory that serves as the reference for triennial reviews and penalty calculations.

How the penalty is calculated

The penalty — technically called SRU levy — is not a fixed fine. It is calculated from the observed deficit relative to the threshold, that is, the number of social-housing units missing to reach 25%. The formula, codified in article L.302-7 of the CCH, multiplies this deficit by a reference value indexed to the municipality's tax potential.

The amount thus calculated is capped by a legal ceiling: it cannot exceed 5% of the municipality's actual operating revenue (raised to 7.5% since the ALUR law for the most lagging and wealthiest municipalities). For a major city with massive revenues like Paris, this cap is rarely reached in practice — but the mechanism exists.

The proceeds of the levy are not lost to housing: they are paid to the Établissement public foncier régional or to a national fund supporting building-friendly mayors, which finances social-housing operations elsewhere. It is a mechanism of redistribution between deficient municipalities and building municipalities, not a penalty for the State's general budget.

The Paris peculiarity: internal pooling

Paris is a single municipality, divided into 20 arrondissements, but constituting a single legal entity in the sense of the SRU law. The 25% threshold is assessed at the whole-municipality level, not arrondissement by arrondissement. This has two practical consequences:

1. Paris meets the law overall (~25% at the City level in 2024, according to the DRIHL SRU inventory), so no penalty applies to the municipality
2. But eight arrondissements are below the threshold (1st, 2nd, 5th, 6th, 7th, 8th, 9th, 16th — see our social-housing geography), with rates as low as 4% in the 7th

This internal pooling is a major legal advantage that Paris owes to its particular administrative status. A typical municipality of 100,000 inhabitants has no redistribution margin — it either reaches the threshold or it does not. Paris can offset the near-absence of social housing in the 7th by a stronger concentration in the 19th.

This mechanism is not neutral. It spares Paris potentially very significant annual penalties (an indicative calculation based on deficient arrondissements shows that a strict arrondissement-by-arrondissement application would trigger tens of millions of euros in levies per year). But it also has a political consequence: arrondissements well endowed with private land have, under this framework, no individual catch-up obligation — production pressure then concentrates on the peri-central arrondissements. The debate on whether to split Paris into several municipalities for SRU purposes is recurrent; it has never succeeded, and would depend on national legislative reform.

The deficiency procedure: when the prefect takes over

If a municipality accumulates delays and the departmental commission, then the national SRU commission, find that the efforts undertaken are insufficient, the prefect can issue a deficiency ruling. This ruling, provided for in article L.302-9-1 of the CCH, triggers three consequences:

1. Multiplication of the levy by a coefficient that can reach 5
2. Transfer to the prefect of the pre-emption right over real-estate sales — the decision to buy a building to convert it into conventioned housing temporarily escapes the municipality
3. Substitution power for the prefect, who can impose construction operations on identified plots

This procedure exists mainly at the level of deficient municipalities in the Paris periphery (Neuilly, Saint-Mandé, Le Plessis-Robinson… according to triennial reviews), and it targets entities where the overall threshold is durably well below 25%. Paris-the-municipality is not concerned, because the overall threshold is met. But it illustrates what would happen if Paris's internal pooling were one day called into question.

How Paris compares

Among the major French cities subject to the SRU law, Paris ranks in the upper-middle European range for the overall share of social housing, as our geographic analysis showed. But the internal heterogeneity between arrondissements is unmatched in other major European capitals:

• In Vienna, the dispersion between districts rarely exceeds 1 to 4
• In London, it rarely exceeds 1 to 6
• In Berlin, the public stock is overall more modest, but more uniformly distributed
• In Paris, the ratio between the 7th (4%) and the 19th (40%) is 1 to 10

This geographic specificity is the direct consequence of the internal pooling allowed by the law: without it, catch-up pressure would have been much stronger on central arrondissements.

Three key points of the mechanism

1. Paris meets the SRU law overall, but not by arrondissement. This nuance, little visible in quick political commentary, is decisive for understanding the absence of penalty at the municipal level.
2. The SRU penalty is not a fine; it is an automatic levy paid to a fund dedicated to social housing — not to the general budget.
3. The deficiency ruling is the truly dissuasive instrument: it triggers multiplication of the levy and transfer of the pre-emption right to the prefect. It applies to durably deficient municipalities, and Paris is not currently among them.

What these numbers do not say

This analysis stops at what the text of the law and public sources (DRIHL, CCH) allow us to say. It does not say:

• The exact amount of the theoretical SRU levy for deficient arrondissements — calculable only with access to tax bases by arrondissement, which are not published as open data at this granularity
• The actual effectiveness of pooling — that is, whether concentrating effort in arrondissements with available land (19th, 20th, 13th) has actually allowed reaching 25% overall, or whether it has simply avoided the political question of catching up the central arrondissements
• What would happen if the national SRU commission decided to tighten its assessment of Paris — case law has not for now settled this question

What it does say, in a sentence: the SRU law in Paris is applied in formally compliant fashion, but through a pooling mechanism that few other municipalities can invoke. That is what makes the Paris situation legally sound and politically contested — two facts that are not contradictory.

Sources: Construction and Housing Code, articles L.302-5 to L.302-9-2 (SRU regime) · Law no. 2000-1208 of 13 December 2000 known as "SRU" · ALUR law of 24 March 2014 · Equality and Citizenship law of 27 January 2017 · Annual SRU inventory published by the DRIHL Île-de-France · Reports of the national SRU commission (triennial review). For rate data by arrondissement, see our article "The 7th at 4%, the 19th at 40%".