Development tax: conversion of buildings into housing and new optional exemptions

Article 115 of the 2026 Finance Act brings conversions of non-residential buildings into housing within the taxable event of the development tax and its filing and penalty rules. It amends the optional exemptions of Article 1635 quater E of the General Tax Code: extension to annexes of social housing and shelters, replacement of the retail shop case by shops referred to in Article 1388 quinquies C, and possible exemption for non-professional garden sheds and greenhouses of 20 m² or less, dovecotes and pigeon houses. It also adjusts procedures (assessment by default, advance ruling). These measures apply from 1 January 2026, except the shops provision and two procedural provisions.