I'm not sure that photoshopping a dog in place of the portrait would qualify to though. It's immediately obvious that it is neither you nor a valid government issued document so doesn't that preclude it qualifying as forgery?
Yes, it is indeed not always clear what constitutes forgery (Germany).
> A document in the classic sense requires an embodied declaration of intent that identifies an issuer and is suitable for providing proof in legal transactions. In the case of a lawyer's letter, the signature is an essential part of the standard repertoire of authenticity.
So removing some parts to make it _could_ make it safe, to Not create a "risk of confusion":
> Even if computer processing creates the appearance of a genuine document, the typical characteristics of the original must be present to establish a serious risk of confusion. Likewise, the BayObLG did not consider the offense of forging evidential data according to Section 269 of the German Criminal Code (StGB) to be fulfilled.
Off topic, but I love how every country has its weird abbreviations that seem obvious but really aren’t, like BayObLG for Bayerisches Oberlandesgericht (Bavarian State Superior Court) or something close to that. Or how every British cop show assumes its audience knows exactly what a DCI is, as in “This is DCI Foxwaddle and I’m DCI Rugby-Botherington, may we have a word?”
Obviously you can go further: What if you just draw up the whole thing with a pencil? What if it's an ID identifying you as a citizen of Nowhereistan? Where does freedom of artistic expression end and a forgery start?
Again, IANAL, but I suppose it would qualify at least as fraud once you try to use even an obvious fake as "proof of identity" in place of a requested government issued document. In that case, there's an intent to deceive that's hard to deny, even if it's just about age verification for access to a digital platform.
I could imagine in court it might come down to details, like whether it's sufficiently similar to a real ID at a glance, or whether tamper-proof marks of an official ID were copied as well.
In any case I wouldn't want to risk up to a year of jail time over a joke.