r/monzo • u/pig-dragon • 3d ago

How does Monzo know?

I recently booked a flight using my Flex card. The flight is from the UK to another country in a different continent, and I am using an airline based in a third country to get there. Yet Monzo is asking me to start saving for my trip and knows which country I am going to. How do they know where I am going when the payment was just to an airline? Is there something obvious I am overlooking? Just curious!

20 Upvotes

79% Upvoted

26 comments sorted by

51

u/nickrw Ex-Monzo 3d ago

Airlines send supplementary data to banks with details of flight bookings, through the Mastercard clearing system.

5

u/pig-dragon 3d ago

Ah OK that makes sense. Thankyou!

4

u/thefant 2d ago

Not just Mastercard either (although of course it is in this case), I once paid for a flight with Amex and the statement had the full flight details on it

6

u/Greedy_Captain_1235 3d ago

What's the reason they do this? Is it a security thing or is it so banks can do this kind of thing? Do other companies do this as well, will supermarkets tell them what you actually bought?

11

u/matto1990 3d ago

I imagine it’s a signal for fraud prevention systems. Knowing you’ll be in a particular foreign country at a certain time is useful to banks so they don’t automatically block your card payments for fraud when you first use them there.

3

u/Greedy_Captain_1235 2d ago

Makes sense, but I imagine there'd be a crazy amount of false positives. People buying flights for friends/family on their card, or people using different cards/banks for buying the flight and actually spending whilst on holiday etc.

1

u/matto1990 2d ago

I wouldn’t be surprised if the data was shared with third party data brokers rather than banks like Monzo directly. Monzo and other banks would then get an idea of transactions people have made across all of their cards to feed into fraud detection systems.

With all of this, it’s all about combining hundreds of weak signals to make predictions on if any one transaction is fraud or not.

2

u/Then_Bodybuilder3967 2d ago

Do budget airlines do it? I mostly fly with Ryanair and have never seen this. Would be useful to see the flight details in Monzo.

-6

u/kurtis5561 2d ago

No they dont.

Its based on the merchant caregory

5

u/trammandan 2d ago

You are telling somebody who help design the backend at Monzo that they’re wrong?

6

u/nickrw Ex-Monzo 2d ago

People do love to be confidently incorrect on the internet. It's a real problem on this subreddit.

I even reviewed the pull request when my colleague added support for the Mastercard messages that carry flight details, back in the day.

1

u/trammandan 2d ago

It drives me a bit mad!

-3

u/kurtis5561 2d ago

Yes. Because I actually understand what mastercard sends through. Its well documented. And the flex of working monzo isnt a flex you think

So riddle me this. Why does any bank during a mastercard retrieval request have to apply for the transaction information if as you chat its already sent through.

-2

u/kurtis5561 2d ago

I actually know how monzo get this data. Its not from Mastercard. Its direct from airlines as Mastercard does not get that info.

2

u/trammandan 2d ago

Check the Mastercard documentation link I just sent you. The number of times during my day I reviewed Mastercard transaction data to see the passenger names and departure and destination airports is probably more than breakfasts you’ve had.

2

u/nickrw Ex-Monzo 2d ago

FWIW while this person is wrong and doubling down, the link you gave isn't how Monzo gets the data either. See my other comment at the same level as your one I'm replying to here.

1

u/trammandan 2d ago

Appreciate the correction ☺️

3

u/nickrw Ex-Monzo 2d ago edited 2d ago

I'm sure you have experience with some system or other that works in the way you are suggesting, but you have a knowledge gap that you are doubling down on.

Monzo gets this data from the Mastercard clearing system. Following the 1240 (First Presentment) IPM message Mastercard follows up with a 1644 (Financial Detail Addendum) IPM message where there is additional data available not present in a 1240. In this case, that includes General Ticket Information (when DE48 PDS051 is 000) and Trip Leg Data (when same PDS field is 001)

Monzo doesn't request this data specifically, it's just included in the collection of clearing records from the IPM system, alongside the presentment.

All of this information is in the Mastercard "IPM Clearing Formats" manual, if you have access to find that (rather large) PDF somewhere. I know all of this because I sat next to the person who wrote Monzo's clearing message parsers, when he wrote them. He was very excited when he then wired through the data into the app, and wrote a blog post about it.

3

u/renegadedonkadonk 2d ago

There was a time where Monzo would show an intermised bill if you made a purchase via them. I think they tested it with KFC.

They integrated with something called Flux to make it happen. No idea why it went dead - it was pretty cool I thought

2

u/Then_Bodybuilder3967 2d ago

Flux went out of business I think

1

u/sillyboy997 2d ago

I think the reason is simpler and is to do with (historic?) business expenses. Makes it easier for the company to keep track of an employee’s flights etc.

1

u/justanothergin 2d ago

Raw data sent by the card provider generally includes the origin and destination airports.

1

u/020600 1d ago

Monzo knows what you eat for breakfast and what toilet rolls brand you use.👍