BERLIN — Faced with a plummeting population, rising labor shortages and widespread emigration, Prime Minister Viktor Orban of Hungary has long taken an unconventional approach to increasing the size and productivity of Hungary’s work force.

He offered university scholarships only to those who promised to stay in Hungary. He gave citizenship to ethnic Hungarians living beyond the borders. And late last year, he increased the amount of overtime employers can demand of workers — to 400 hours a year.

But on Sunday, Mr. Orban announced one of his most ambitious plans yet: Any Hungarian woman with four or more children will no longer pay income tax.

Anything to avoid immigration.

“We are living in times when fewer and fewer children are being born throughout Europe. People in the West are responding to this with immigration,” Mr. Orban said in a speech on Sunday. “Hungarians see this in a different light. We do not need numbers, but Hungarian children.”