Pay 30 percent of your income for rent. Not more. For nobody. Sounds good and fair. Is that now the formula to stop the rent madness in Berlin? So easy?

The 30 percent limit is particularly brilliant as a political maneuver. The Governing Mayor Franziska Giffey scores with this suggestion. Other proposals from their coalition partners, the Greens and the Left, have been forgotten, such as a general rent freeze, a pause in rent increases or at least capping them at one percent.

Giffey’s proposal is also good because it links the permissible rents to the individually available income. This rules out the absurdities that the rent cap had made possible: the Berlin law also halved the rent of the top manager with a salary in the millions for his second home on Kurf├╝rstendamm. Such regulations are at the expense of the landlord. By no means all of them have money in abundance. Landlords also have to pay for the ecological conversion of the housing stock.

So can everyone be happy about the new simple and fair formula?

Renters probably not. Because there will be no regulation or law with fines or sanctions. The government ruled that out. Good thing, because a law would fail in Karlsruhe. The regulation of rents is exclusively a matter for the federal government. With this justification, the judges at the Federal Constitutional Court had already overturned the rent cap.

Instead of coercion, Giffey wants to lure the housing industry with charm and concessions in the regulations of the construction industry. The proposal didn’t come out of nowhere. It is negotiated in the “Alliance for New Construction and Affordable Rents” that the government has convened. Giffey’s partners, the landlords in this case, should voluntarily agree not to charge more than 30 percent of the income from their tenants.

Is this realistic? Some will, some won’t. The well-intentioned test center can admonish and warn stubborn refusers of the upper limit. But she can’t enforce anything.

Sure there will be moral pressures. And maybe even the majority of Berlin’s tenants will benefit from the new border if the self-commitment actually remains in the agreement on the conclusion of the alliance. Nevertheless, it will not stop the rise in rents on the market. Because there are enough people with higher incomes in Berlin and not enough apartments at low rents.

In addition, some landlords are dependent on the high rents in order to be able to pay for loans or energy renovation. Some also take what they can get – simply because they can. Especially if it is not expressly forbidden and not prosecuted.

The devil is in the details. Tenant representatives, for example, criticize the fact that households with very little income have hardly any money left to live on, even with a rent burden of 30 percent – and are calling for a staggered burden limit, starting at 20 percent.

It is therefore exciting to see whether the self-commitment will come and whether Giffey can sell it as a success, despite the rather mixed reality check. It will be decided in two weeks whether the Left and the Greens will allow her that.