Your Ex Has the Kids Half the Week, But Not Their Tax ID: How Access Actually Works

The Official Rule

Every child in Germany gets a Steuer-Identifikationsnummer, a lifelong tax ID, and the confirmation letter is mailed to whatever address is currently on file for that child, in practice, the household the child is registered as living with. For separated or divorced parents, this creates a genuinely common friction point: the parent who doesn’t share that address often needs the number too, for their own Anlage Kind or other tax filings, and doesn’t automatically have it.

The Bundeszentralamt für Steuern (BZSt) does have a process for this, but it requires you to actually prove custody, not just assert it. To get a copy of the ID redirected to your own address, you submit a written declaration that you hold Sorgerecht, custody, along with documentation to back it up, either your divorce decree or your custody arrangement, submitted as a copy. This isn’t a formality you can skip by just explaining your situation over the phone.

If you genuinely don’t have custody, you’re not actually stuck, there’s a real fallback. You can tell your local Finanzamt that you don’t have your child’s Steuer-ID, and they’re able to look the number up internally for their own processing without disclosing the actual digits to you. This matters because it means you don’t need to negotiate with the other parent just to get your own tax return processed correctly.

The underlying reason for all of this friction is data protection, not bureaucratic inertia. The BZSt has been explicit that it won’t disclose a child’s ID to a parent without custody, and won’t even confirm to an unauthorized third party whether a specific person has an ID assigned at all. Requests with the correct documentation go to a specific department: Bundeszentralamt für Steuern, Referat St II 3, 11055 Berlin.

What Real People Say

Parents navigating this after a separation consistently describe the same practical lesson: gather the custody documentation before you contact the BZSt, rather than expecting a phone explanation to substitute for it, since the written declaration and proof requirement is applied consistently regardless of how clear-cut the custody situation actually is.

The Finanzamt-lookup fallback for parents without custody is less widely known, and comes up in practical guidance as the detail that saves people from assuming they have no path forward at all when the other parent isn’t cooperative about sharing the number directly.

Step by Step

1. If you have custody and need the Steuer-ID redirected to your address, gather your divorce decree or custody arrangement as a copy first.
2. Submit a written request to the BZSt (Referat St II 3, 11055 Berlin) declaring you hold custody, with your documentation attached.
3. If you don’t have custody but still need the number for your own tax filing, contact your local Finanzamt directly rather than trying to get the BZSt to disclose it to you.
4. Don’t expect a phone call alone to resolve this, both paths, custody-based redirection and the Finanzamt lookup, generally require something in writing.
5. If you’re unsure which path applies to your specific custody arrangement, it’s worth confirming directly with the BZSt or your Finanzamt rather than guessing.

Compliance Note

This page explains the general process for accessing a child’s Steuer-ID as a separated or divorced parent, but individual custody arrangements and Finanzamt practices can vary, and this isn’t legal or tax advice. For your specific situation, confirm directly with the BZSt or consult a tax advisor.