CARF nexus follows your establishment, not your users. Here's the residence-to-branch hierarchy, why you report in one jurisdiction, and how it plays out.

Almost every CASP reading CARF for the first time believes the same wrong thing: that you report to each country your users live in. You don't. What settles the question is where your business is established, and your customers' locations don't enter into it. In almost every case that means one jurisdiction. Get it wrong and a team starts bracing for 30 filings when the real answer is one, so it pays to go through this slowly.
CARF borrows this idea from the Common Reporting Standard it's modelled on. It defines when a Reporting Crypto-Asset Service Provider has "nexus" with a jurisdiction. Nexus is what obliges you to report there, and you test it against your own establishment, in a set order:
Work down the list and stop at the first one that applies. Notice what's missing: where your users live. A German-resident exchange reports in Germany. An exchange incorporated and managed in Ireland reports in Ireland. Your office, your management team, a branch, those are the things that pull you into a jurisdiction. The customer map doesn't.
Because the tests run in order, a provider that touches several jurisdictions still lands in one reporting jurisdiction, the highest one it hits. Then CARF layers on tie-breaker rules. A provider with nexus in more than one place doesn't file the same data twice: if you're already reporting the information in a jurisdiction with an equivalent framework, you're relieved from reporting it again elsewhere. Everything about the design points toward a single filing.
That single filing is where your users' residence finally counts for something. You report your reportable users to your own authority, and the OECD Common Transmission System exchanges each user's data onward to the jurisdiction where that user lives. So residence decides two things: who's reportable, and who ends up receiving the data. Where you file isn't one of them. We cover who counts as reportable in the self-certification and TIN validation workflow.
Every non-EU exchange asks the same question: what happens when you've got no establishment inside a regime but plenty of users there? DAC8 answers it head-on. A crypto-asset service provider that isn't resident, incorporated, managed or branched in the EU, yet has EU-resident users, registers in a single member state of its choosing and reports there for all of them. Pick a member state, file once, and it shares the data with the rest. The wider OECD network handles its participating jurisdictions the same way.
A handful of worked examples make the pattern obvious.
Every time, the count of filing jurisdictions comes out to one. The entity decides it. The user base doesn't.
Two jobs, really: pin down your own nexus jurisdiction correctly, and then, inside that one filing, work out which users are reportable and which jurisdictions their data has to reach. Our CARF and DAC8 reporting platform handles the second job. It determines reportability from validated residence data and routes each user to the right destination, so one submission reaches every jurisdiction that should get it. When a user won't certify their residence, the 60-day rule decides what happens next, and the deadlines by jurisdiction tell you when each filing is due. The OECD exchange-of-information hub and the EU tax cooperation pages are the primary sources.
No. You file in one jurisdiction, the one where your business has nexus. Your users' residences decide which of them are reportable and where their data gets sent, but the filing itself happens once, with your own authority.
Your own establishment, tested in a set order: tax residence, then incorporation, then place of effective management (where your senior team actually runs things), then a regular place of business such as a branch. Stop at the first that applies. User location doesn't enter the test.
Under DAC8, a provider with no EU establishment but EU-resident users picks a single member state and reports there. That member state shares the data with the others, so you're still filing just once.
No. CARF's tie-breaker rules spare you from reporting the same information twice. If it's already being reported in a jurisdiction with an equivalent framework, you don't have to report it again elsewhere.

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