Your Kid Wants Their Own Phone Number: What's Actually Legal at Each Age

The Official Rule

Getting a child their own phone number runs into two separate legal thresholds in Germany, one about contracts generally, and one specifically about data protection, and understanding both helps you pick the actually workable option rather than running into an invalid contract or an unexpected consent requirement.

Full legal capacity to sign a contract independently doesn’t arrive until age 18, and mobile phone contracts are treated no differently. A contract signed by a minor without parental consent is legally described as “schwebend unwirksam,” pending invalid, which in practice means the arrangement doesn’t stand on its own, a parent or guardian effectively remains behind it regardless of whose name appears on the paperwork or which line the child actually uses day to day.

Prepaid is where the age line actually changes what a child can do on their own. From age 16, a teenager can independently purchase a prepaid SIM card, no parent needs to be part of that specific transaction. Below that age, a parent’s involvement is genuinely required to get a prepaid SIM at all, this isn’t a formality that gets waved through, it’s a real requirement providers apply.

Data protection law adds a second, related but distinct age threshold worth knowing separately from the contract question. Under the GDPR, a minor can only independently consent to their own personal data being processed by an information society service provider from age 16 onward. For anyone younger, a parent or guardian has to provide that consent instead, this matters for app accounts, online services, and anything requiring data-processing consent, not specifically for the SIM or phone contract itself, but it’s worth keeping in mind as a related consideration when a younger child starts using their own device.

eSIMs simplify the practical side of all this regardless of which legal threshold applies. Activation happens by scanning a QR code rather than physically inserting a card, which also means there’s nothing small and easy to lose the way a physical SIM can be. Some providers make this genuinely convenient for families specifically, Deutsche Telekom’s PlusKarte is a commonly cited example, adding an eSIM to an existing family plan at no additional cost.

Given all of this, the practical route most families actually land on for a younger child is an additional card (Zusatzkarte) tied to a parent’s own existing contract, rather than attempting any kind of standalone arrangement in the child’s name. This keeps legal responsibility automatically and clearly with the parent, avoids the “pending invalid” contract question entirely, and bills everything to one shared account rather than creating a separate billing relationship for a child who can’t yet independently hold one anyway.

What Real People Say

Parents setting up a first phone line for a younger child consistently describe the Zusatzkarte approach as the option that actually made sense once they understood the underlying legal picture, rather than something they’d have chosen by default without knowing a standalone contract wouldn’t be valid without their consent anyway.

The eSIM-and-family-plan combination comes up often in practical discussion as removing a genuine point of friction, a lost or damaged physical SIM used to mean an actual trip to a shop or a wait for a replacement, and providers offering free eSIM addition to an existing family plan have made this meaningfully simpler for families managing multiple children’s lines.

Step by Step

1. For a child under 16, plan on an additional card (Zusatzkarte) tied to your own contract, rather than attempting a standalone plan in their name.
2. For a teenager 16 or older who wants more independence, prepaid is genuinely available to them directly, they can purchase it without a parent present for that specific transaction.
3. Remember the GDPR consent threshold is also 16, and separate from the SIM question, younger children need your consent for data processing on apps and services they use.
4. Ask your provider specifically about eSIM options for family plans, several add this at no extra cost and it removes the physical-SIM loss risk entirely.
5. Don’t attempt a standalone contract in a minor’s name expecting it to stand on its own, without parental consent it’s legally pending invalid regardless of the provider’s willingness to issue it.

Compliance Note

This page explains the general legal framework for minors and mobile contracts, SIM cards, and related data protection consent in Germany, but this is not legal advice, and specific provider policies can vary. For your specific situation, confirm current requirements directly with your chosen provider.