The latest changes made to the redesign of Dublin's bus network could cost an extra €40m.
Changes to Bus Connects were announced last month after concerns from thousands of people.
The National Transport Authority says it will mean a 22% increase in services.
Anne Graham from the National Transport Authority says those changes mean more funding will be needed.
"We would expect that that funding would be put in place because it's in the order of €30-€40m additional PSO funding just to fund the operational costs associated with that increase."