RER B: What SNCF Promises on Punctuality and How to Choose Your Home

Are you weighing several communes in Île-de-France served by the RER B? This article helps you read the punctuality target announced by SNCF correctly, test a line before signing a lease, and calculate your transport costs. It also tells you what the file does not let us claim, and where to check.

What SNCF has actually announced for the RER B

On Thursday, October 15, 2026, SNCF Voyageurs and Île-de-France Mobilités approved a new contract for the 2026–2030 period^[1]. For the RER B, the trajectory set out in the contract is as follows: 89% punctuality in 2026, 90% in 2027 and 2028, then 90.5% in 2029 and 91% in 2030^[2].

On resources, €7.2 billion in investment is planned for 2026–2030, which is 20% more than the previous contract^[1]. The arrival of the new MI20 trains, built by Alstom, is expected to help improve punctuality on a line that has regularly faced reliability problems^[2].

Keep in mind what kind of figures these are: they are targets written into the contract, not observed results. The press itself points this out: the question remains whether these commitments will actually translate into an improvement in users' daily lives^[1].

Reading a punctuality rate: what 89% or 90% means (and doesn't mean)

A target that rises by roughly half a point a year on average (from 89% in 2026 to 91% in 2030) gives an order of magnitude of the ambition, not a guarantee of a trip without delays. An overall rate tells you nothing about the specific trip you will make, the time you will make it, or the day of the week.

To track whether the commitments are kept, Île-de-France Mobilités will have new weekly and monthly reports^[2]. These reports were not reviewed for this article: they are the right starting point for comparing, once published, the promise and the reality.

Judging a line's reliability before choosing your home

• Check the line's official channels (Transilien page, Île-de-France Mobilités) for ongoing disruptions and announced works: these pages were not reviewed for this article, so verify what is published there.
• Find on the map the sections you will actually travel on, and check whether other lines share them.
• Make your real home-to-work trip at peak hours, on several different days, before you sign.
• Compare several served communes and look, from each home, at what other transport options exist.

The actually observed punctuality figures for the RER B and the breakdown of its operation are not presented here: these points should be verified with Île-de-France Mobilités and SNCF.

Organizing your daily commute: passes and budget

Since January 1, 2026, a Métro-Train-RER single ticket in Paris costs €2.55 at full fare, and a Bus-Tram ticket costs €2.05^[3].

For regular trips, the monthly Navigo pass covering all zones costs €90.80 in 2026, up from €88.80 in 2025. The weekly all-zones Navigo is €32.40, and the annual one is €998.80, or about €83.23 per month^[4].

The right choice depends on how often you are actually there. If you work on site every day, compare a pass with paying per trip. If you work from home part-time, do the math on your travel days: for example, at €2.55 per trip, a round trip costs €5.10 with single tickets^[3], to compare with the price of a pass for the number of days you spend on site. The weekly pass is valid for one fixed week, Monday to Sunday^[5].

Planning a backup when the line is disrupted

Here is a method, not a list of routes.

• Before choosing a home, identify from the address at least one other transport option (another station, bus, tram) and note how long it would take you.
• Keep a margin in your budget for these exceptional trips.
• Check disruption information on the line's official channels before you leave: their content could not be verified for this article.

Points to watch: targets, compensation, and fares

A contractual target is not a guarantee of a trip without delays: 89% or 90% are targets announced for 2026 and 2027, and nothing guarantees they will be met^[2].

Compensation depends on conditions. The contract maintains refund mechanisms in the event of significant disruptions: a lasting decline in punctuality, a prolonged strike, or exceptional disruptions may lead to compensation of up to 1.5 times the price of the monthly Navigo pass^[2].

The weekly pass's zone extension only applies during specific periods: weekends, public holidays, short school holidays, and from July 15 to August 15^[5]. This pass does not include Orlyval, Bus Direct Paris-Airport, VEA Disney shuttles, or tourist buses^[5].

Prices change: the monthly Navigo rose by €2 in 2026^[4], and the press indicates the pass should soon see another price increase^[1]. Don't budget based on the current price for several years.

Aid and Reimbursements for Commuting

The Île-de-France Mobilités page on the weekly pass states that employers must reimburse at least 50% of the cost to employees for the zones needed for home-to-work commutes^[5].

To measure the net cost of your commute based on your status, check the detailed rules (rates by sector, situation for full-time remote workers and freelancers) with your employer and on official sources before choosing housing.

• Test the actual commute during peak hours, over several days.
• Identify a transport alternative from each candidate home.
• Compare a pass with pay-per-trip based on your days in the office.
• Ask your employer what they reimburse.
• Check Île-de-France Mobilités punctuality reports as soon as they are available.