Two towns in Baden-Wuerttemberg are running the publicly funded scheme, aimed at both supporting family life and reducing the shadow economy.
Employees covered by social insurance get a subsidy of 8 euros (Â£6.7; $8.6) an hour for additional time worked.
The vouchers can exchanged at agencies supplying domestic services.
Ralf Kleindiek, state secretary in the federal ministry of family affairs, stressed that the goal was to "support qualified women who are heavily involved in family work but would like to return to work or do more work".
Launched last month, the project is due to run until February 2019, the Frankfurter Allgemeine (FAZ) newspaper reports (in German).
It was inspired by a similar scheme in Belgium, the family affairs ministry said in a press release (in German).
Employment agencies issue vouchers to eligible employees in the towns of Aalen and Heilbronn, the FAZ reports.
The vouchers can then be redeemed by service agencies whose staff have social insurance.
Between 75% and 83% of helpers employed in German households are unregistered, according to an estimate by the German Business Institute in Cologne, quoted by the paper.
"With professional help in the home, it is easier to reconcile work and family life," said Dr Kleindiek.
"On the other hand, we are strengthening service companies with the pioneering project and effectively combating illegal work, since the vouchers may only be redeemed where the companies employ their employees with social insurance."
Service vouchers have reportedly enjoyed success in Belgium since they were introduced in 2003.
Employees working extra hours are to get vouchers to help with housework such as cleaning and ironing under a pilot scheme in south-west Germany.