A little-known clause in Germany’s new military service law that requires men aged 17 to 45 to seek permission from the armed forces before staying abroad for more than three months has caused a huge backlash.

The Military Service Modernisation Act that took effect on 1 January is part of broader reforms aimed at strengthening the military.

According to the German newspaper Frankfurter Rundschau, which first pointed this out, the government says the measure is mainly a precaution to ensure authorities can track potential recruits if needed, especially if voluntary enlistment fails and conscription is reconsidered.

The law requires 18-year-olds to complete a questionnaire to assess their suitability for service, though full conscription has not been reintroduced.

A defence ministry spokesperson said: “According to the wording of the law, males aged 17 and over are obliged to seek prior approval from the relevant Bundeswehr (armed forces) career centre for stays abroad lasting longer than three months.”

Officials have stressed that the rule has no real practical impact for now: there are no penalties, approvals are expected to be routinely granted, and it mirrors a largely unused Cold War-era regulation.

“The regulation already applied during the cold war and had no practical relevance; in particular, it is not subject to sanctions.

“We will clarify through administrative regulations that authorisation is deemed to have been granted as long as military service is voluntary.

“As military service under current law is based exclusively on voluntary participation, such authorisations must, in principle, be granted,” the spokesperson reportedly said.

Despite these assurances, the clause has triggered public concern and protests, particularly among young people.

The clause could impact millions of Germans planning extended stays overseas, whether for a gap year, studying abroad, a new job or a sabbatical.

The requirement is rooted in Germany’s 1956 Conscription Act, which has been amended multiple times, most recently in December. Before this latest change, the obligation to report extended stays abroad applied only during a state of national defence or mobilisation.

On Reddit, observers had varied responses to this clause.

One user wrote: “So…are we all just going to fax an application for three months every day? I mean, that’s only 20-30 million applications per day, it should be easy enough.”

The defence ministry’s statement acknowledged that the implications for young people in the country could be “far-reaching” and said rules on exemptions were being drafted, partly to “avoid unnecessary bureaucracy”.

Germany is stepping up its military readiness, with plans to expand its conventional forces in response to threats from Russia and uncertainty over the future of Nato.

The new rule is intended to ensure the state can track and, if necessary, limit the movement of men of fighting age during a national emergency, such as a war that could require rapid conscription.

The government says the aim of the reform is to expand the size of the armed forces from around 184,000 personnel to between 255,000 and 270,000 by 2035.