Makhmadsaid Ubaidulloyev, speaker of the upper house of parliament, said the government could raise about $10 million for its construction if all residents of the capital Dushanbe were to give up half their wages in May and June.
"Makhmadsaid Ubaidulloyev appealed on all companies to transfer 50 percent of employees' salaries to help Rogun's construction," said Shavkat Saidov, a Dushanbe city spokesman.
One of the world's poorest countries, where the average monthly wage is about $63, estimates the cost of completing Rogun at between $1.3 and $3.2 billion.
Saidov said the measure was voluntary but some people said they feared that the money would be withdrawn automatically.
"Who is going to ask us? They will take it out of our salaries and that's it," said Nagina, a mother of three who spoke to Reuters on condition of anonymity.
The Rogun plant, started in Soviet times but never finished, is key to Tajikistan's goal to become a significant regional electricity exporter and raise aluminum production.