Taiwan has been excluded from the World Health Assembly since 2017 due to opposition from China, which regards the democratically self-governed island as a renegade province.
Both the Japanese and U.S. governments have voiced support for inviting Taiwan, saying the international community could learn from its success in bringing COVID-19 under control.
But neither have formal diplomatic relations with Taipei, and Tokyo especially is wary of offending Beijing, its biggest trade partner.
The strategic dialogue at the legislative level, which had been slated to take place last year after Taiwanese President Tsai Ing-wen won re-election but was postponed due to the pandemic, is a way to strengthen ties without openly challenging China.
According to the sources, the Japanese and U.S. lawmakers plan to call on Taiwan, a major producer of semiconductors, to provide stable supplies of the key electronic components amid concern that rising tensions between Washington and Beijing could disrupt supply chains.
Also expected to be on the agenda is Taiwan's potential participation in the Trans-Pacific Partnership, an 11-member free trade agreement covering about 13 percent of the global economy.
Representing Japan will be Keiji Furuya, who heads a group of lawmakers working to advance ties with Taiwan. Minoru Kihara, a special adviser to Prime Minister Yoshihide Suga, could also attend.
Taiwanese Legislative Speaker You Si-kun and both Democratic and Republican members of the U.S. Congress have been invited to the meeting, the sources said.