Walking instead of driving may be cheaper in most circumstances, but prostitutes in the western German city of Bonn aren't escaping the cost of taking up street and sidewalk space.  

City council has instituted a new tax on sex-trade workers who take to the streets at night to attract customers.  

Under the new system, a prostitute must put the equivalent of $8.70 US a night into one of many converted roadside vending machines that formerly dispensed tickets to drivers, in a move expected to raise an estimated $270,000 annually for the city.

The machines show the times of day a ticket must be purchased: from 8:15 p.m. to 6 a.m. each day of the week.  

The Telegraph quotes Monika Frombgen, a spokeswoman for Bonn council, as saying the meter system is meant to tax street prostitutes on the same level as sex-trade workers in registered establishments.

"This is an act of tax fairness," the British daily's website reported Tuesday. "Prostitutes in fixed establishments such as brothels and sauna clubs already pay tax."

Previous attempts to tax street prostitutes have failed, primarily because foreign-born ones couldn't understand the income tax forms, Frombgen said, adding that the new meters are easy to use.

Any prostitute looking to evade the new tax system better think twice: inspectors will monitor meter use by approaching street workers to ensure they are carrying tickets. Anyone caught without one will receive a warning on a first offence, and subsequently will be fined or banned from practising their trade.

Bonn is believed to be the only city in Germany with this new meter tax system, although Dortmund requires prostitutes to buy tickets from gas stations.