The indices are the fruit of a partnership, officialised by two conventions, between the notarial profession (High Council of Notaries and Paris Chamber of Notaries), which records the data collected during real-estate transactions, and INSEE, which contributes its methodological skills.
The vast majority of property transactions are housing transactions, with houses and apartments in fairly equal proportions. Some of the remaining transactions cover other types of property (garages, commercial premises, entire apartment buildings, plots, etc.), but these are not included when calculating the price indices.

Quarterly

Since the last update, the geographical scope is France (excluding Mayotte).

A considerable amount of work goes into the process between drawing up a deed of sale and publishing the final index. Each of the 5,500 notarial offices was invited to send a copy of every deed of sale, either by post, or in a paperless format, as has become more common since 2010. The speed with which each office sends in the data is crucial for the quality of the index: a deed that arrives too late for the quarter being considered is not used when calculating the index. Hence the advantage of paperless systems, which avoid delays from grouping batches of deeds together and postal delays; the majority of deeds are now sent in this way.

The Notaires-INSEE second-hand housing price index is based on a methodology validated by the Scientific Board of the Notaires-Insee indices (Conseil scientifique des indices Notaires-Insee – CSIN).