Is Aufenthaltserlaubnis really necessary?

What is the worst thing that is likely to happen to a non-German, non-EU resident of Berlin who does not have an Aufenthaltserlaubnis/Aufenthaltsgenehmigung? I ask because I suspect I will have trouble getting one (I have health insurance through my employer, but it is American and it sounds from other forums that it won't pass muster here, although I am covered against anything really dire). I am therefore wondering if I will ever need it for anything ordinary and whether it is worth risking not having one. Up to now, the Meldeschein has been necessary, but not the Aufenthaltserlaubnis. I will not be working in Germany, but living here for a year. Thanks.

means you will be residing in Germany for a year. You will require residence permit to be able to do that.

i think the tourist visa has a limitation of 90 days, and that will not work for you as you want to stay a year in Berlin.

You need an Aufenthaltserlaubnis. Even if you get through the entire year without getting caught, when you leave Germany to return to the US, German immigration authorities will check your passport and see that you entered a year ago and never got a residency permit.

And you will have to pay a fine and you will be banned for 5 years in the whole EU.

For what it's worth, my passport was not stamped when I entered the Schengen zone, so I don't see any way that a customs official would be able to determine how long I had been in Germany. But it seems that the hassle and cost of getting acceptable health insurance (I have perfectly good health insurance in the US, which covers me in Germany, but it seems from many other posts that it is unlikely to pass muster for an Aufenthlatserlaubnis), is probably worth the risk. Thanks for your advice.

In all likelyhood your passport was scanned and the relevant information stored in the SIS database ...

they scan the barcode. You will be on their computer.

edit: wot miwald sed.

You just found out how to cheat the system!!!

Nothing to do with customs officials in Europe (Zoll in Germany).
Its the immigration officials who will be interested...