Germany Counts Heads and Finds 1.5 Million Fewer Residents Than Expected

BERLIN — It’s as if Leipzig, Hanover and Dresden had disappeared in the blink of an eye, statistically speaking.

Germany, which has been deeply concerned about its rapidly dwindling population, released the results of its first census in nearly a quarter of a century on Friday and found 1.5 million fewer inhabitants than previously assumed.

Chancellor Angela Merkel was already worried about the shrinking numbers of taxpayers and able-bodied workers. How future smaller generations will repay German debts, much less the mounting liabilities and guarantees meant to contain the euro-zone debt crisis, is a central question here.

Germany had not conducted a single census count since reunification, not even an effort to tally those in the former East Germany after the Berlin Wall fell in 1989. The disappearance of 1.5 million people, equal to almost 1.9 percent of the population, only exacerbates the longer-term downward trend.

How a country known for exactitude could miss so badly on something as simple as its population is a result of another German preoccupation: privacy. The last census, in 1987, was strenuously opposed by those who believed the government should not monitor citizens. The latest, conducted in 2011, came about only because the European Union required it.

“Who shrunk Germany?” asked a headline on the Web page of the newspaper Bild after the news was announced, the beginning of a demographic detective story that ends with no individual mastermind but millions of culprits guilty only of bureaucratic oversights and omissions.

The census news, that Germany has 80.2 million people rather than 81.7 million, was announced by the Federal Statistical Office. Most of the missing people appeared to be migrants.

But the discovery of fewer migrants than previously thought does not affect the demographic repercussions on the economy or broader questions about the integration of Germany’s migrant populations.

Anyone who moves to Germany or even within the country is expected to register an address with the local municipality. Without proof of registration even simple steps like opening a local bank account can be impossible. Deregistering is required when moving out, but the step is easily skipped, especially for those with no intention to return.

In particular, foreigners who registered when they moved in, as required, apparently were leaving the country without ever deregistering. In the process they created what statisticians here call “card-index corpses,” phantom residents who lived on in the records long after having departed the country.

“Demographers were trying to explain the healthy-migrant effect, why they were living to be 110 years old,” said Steffen Kröhnert, a social scientist at the Berlin Institute for Population and Development. “It turns out they had moved back to their home countries and were only living in the registries.”

A rise in migration to Germany as job seekers from recession-racked countries like Spain and Greece sought work was one of the few bright spots, and it will have to be re-evaluated in light of the new figures. Germany is home to 1.1 million fewer foreigners than previously thought and 428,000 fewer Germans than expected, the study found. In all nearly 6.2 million foreigners live alongside roughly 74 million Germans.

The results reinforce a widespread belief in Germany that, although the country is the European Union’s most populous and the Continent’s largest economy, demographic decline poses special challenges. While politicians and economists in Paris and Washington call on Germany to spend more to pull the European economy out of its slump, Germans say they have to keep saving to prepare for the long run.

Who will pay for the pension system is an even more urgent question in Germany than in the United States, where the growth of the elderly population has raised worries about the future of Social Security. Germany has one of the lowest birthrates and oldest populations.

The Nazi regime abused demographic information. During the cold war, many on the political left believed that German law enforcement had been overzealous in the methods used to track down the terrorists of the Baader-Meinhof gang. The result was a backlash against the collection of personal data.

Shortly before a census was scheduled to begin in 1983, a court order disrupted it on the grounds that census data might be shared with other government authorities, like the police or tax examiners.

During the debate in the prelude to the 1987 census in what was then West Germany, the police seized Green Party pamphlets that declared, “Only sheep are counted.” A raid on an office calling for a boycott of the census resulted in rioting in West Berlin that caused millions of dollars in damage and left 100 wounded and more than 50 in jail.

Opposition remains, though it is milder today. Peter Schaar, the federal commissioner for data protection, said the data collected in the census should be deleted as quickly as possible, the daily newspaper Die Tageszeitung reported. “If the reference numbers that every citizen received for the census are saved for the long term, the danger of abuse indeed arises,” the paper quoted Mr. Schaar as saying.

German officials believed that the registries kept by all municipalities had given them a good idea of resident populations. The authorities tabulated births, deaths and officially reported relocations, and they adjusted the old figures as best they could. Mistakes compounded, and incorrect assumptions hummed along undetected.

“These striking deviations alone clearly show how important a readjustment of population and housing data is,” said Roderich Egeler, the president of the Federal Statistical Office.

“The numbers,” said Mr. Kröhnert of the Berlin Institute, “are definitely more serious than we thought.”

A version of this article appeared in print on June 1, 2013, on page A4 of the New York edition with the headline: Germany Counts Heads and Finds 1.5 Million Fewer Residents Than It Expected.