Morawiecki told US broadcaster CNN in an interview that he wanted young people to stay in Poland rather than emigrating.
Poland does not want to be an "ageing" or "dying" country but a nation with a future, he added.
The new tax rules came into effect on Thursday.
President Andrzej Duda last week signed into law the plan by the country’s governing conservatives under which Poles under 26 who make less than PLN 85,528 (EUR 19,937) a year will be exempt from the country's 18-percent income tax.
Many young and educated Poles left abroad in search of better paid jobs as Western labour markets opened up to them after the country joined the EU in 2004.
The change in tax rules is part of a string of spending pledges announced by the Polish government earlier this year.
(pk/gs)
Source: IAR