The German citizen, a resident of Main-Kinzig county near Frankfurt, is accused of having "supported the cruel and malicious killing of thousands of prisoners as a member of the SS guard detail", prosecutors in Giessen said in a statement on Friday.
They did not release the suspect's name.
He is charged with more than 3300 counts of being an accessory to murder between July 1943 and February 1945.
The indictment was filed at the state court in Hanau, which will now have to decide whether to send the case to trial.
If it does, he will be tried under juvenile law based on his age at the time of the alleged crimes.
Prosecutors said a report by a psychiatric expert last October found the suspect was fit to stand trial at least on a limited basis.
German prosecutors have brought several cases under a precedent set in recent years that allows for people who helped a Nazi camp function to be prosecuted as an accessory to the murders there without direct evidence they participated in a specific killing.
Charges of murder and being an accessory to murder are not subject to a statute of limitations under German law.
More than 200,000 people were held at Sachsenhausen, just north of Berlin, between 1936 and 1945.
Tens of thousands died of starvation, disease, forced labour, and other causes, as well as through medical experiments and systematic SS extermination operations including shootings, hangings and gassing.
Exact numbers for those killed vary, with upper estimates of some 100,000, although scholars suggest figures of 40,000 to 50,000 are likely more accurate.
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