Eric but at Bunq, the deposit it at a "in between account" so they can earn extra with that money I think.
Not really what is happening here. I'm gonna assume you're talking about Dutch banks. So when transferring money between different banks, there are clearing systems in place to facilitate these transfers. Let's start with the most basic system.
Nearly all European banks can make regular SEPA bank transfers by means of using the STEP2 clearing system of EBA clearing. This is the standard method that takes up to 1-2 business days. There are certain clearing windows during the day, you can see more info here: https://www.ebaclearing.eu/services/step2-sct/settlement-and-processing-cycles/ They start at 6am in the morning until 4pm in the afternoon, roughly every 150 minutes. (On business days, not weekend or holidays.) But not every bank has to partake in every cycle, some banks only participate in a single cycle every day. That can lead for example to the following situation:
- Bank A customer starts transfer at 3pm on day 1.
- Bank A send the payment info to STEP2 during the next cycle on 4pm on day 1. (The payment is now in the clearing system.)
- Bank B only subscribes to a single cycle at 4pm every day, so they will not get the payment immediately. They will get it with the next 4pm cycle on day 2. Then the money will be credited to their customer's account.
Obviously if there was a weekend in-between day 1 and 2, the delay is quite high. But that is how regular SEPA bank transfers work. No "in between account" at bunq, just the clearing system taking its time. bunq does subscribe to all 5 day-time cycles of STEP2, btw, so depending on the other bank, the money sometimes only takes a few hours to be sent. But it always depends on both banks and what clearing cycles they subscribe to.
You also said that with other banks the payments are instant. That is because there are two other relevant systems that I haven't talked about yet. Namely the instant payment schemes of the Dutch banks and the European instant payment system. As you can guess from the name, these systems allow for almost instant payments that reach the other bank in seconds. No longer do you have to wait for cycles, but transfers are sent immediately and the banks are hooked up to the system 24/7/365. It only works, though, if both banks of sender and receiver are hooked up to the same instant payment system.
While bunq is only connected to the European instant payment system, most other Dutch banks are only connected to the Dutch instant payment system. The only exception is ABN Amro, who are connected to both systems. So when you send a payment from bunq to for example a German Sparkasse account, it will be sent instantly in seconds, because both are connected to the European system. But if you send money from bunq to Dutch ING, the payment has to go through the STEP2 system that I described above. Then it takes 1-2 business days. Not because bunq is magically generating interest out of delayed payments, but because there is simply no way to send money faster to ING with the systems that they're connected to.
While you could argue that bunq should just join the other Dutch banks and also connect to their instant payment system, from a European perspective, the Dutch banks are behaving special here. So bunq actually can send instant payments to much more banks than other Dutch banks (except ABN, of course).