Housing charity Threshold says its number of calls trebled in the last three weeks of March.
It says the majority of people are now afraid of falling into rent arrears due to a loss of income because of the Covid-19 pandemic.
The charity is now fearing a spike in the number of homeless people after the government's measures to protect renters are lifted.
Threshold chief executive John-Mark McCafferty says the types of calls they are getting have changed.
"Most tenants impacted are seeking advice on rent supplements followed by fears about tenancy terminations," said Mr McCafferty.
He said that they are coping with the demand as there has been a drop in other work in relation to the Residential Tenancies Board (RTB) and the Workplace Relations Commission (WRC) and other representative work.
"We are very mindful of that trebling in calls in the last three weeks in March and into April because of the ramping up of the number of people who approaching us who were doing fine a month ago."