The cost of a monthly pass in Paris for the Metro, RER or bus network that covers all of zones one to five is €70, no matter where you live.
When the €70 price was fixed last year it was heralded as a victory for commuters, especially those living out in the poorer suburbs, for whom the price of a monthly pass was reduced fairly dramatically.
But there were questions of whether the state could really afford to set such a seemingly low price.
And those questions remain.
Valérie Pécresse, the head of the Paris regional authority, has even threatened to raise the price of the pass by €10 to €15 in an interview with Le Parisien newspaper.
"The €70 pass was just improvised by the left before the regional elections and was never funded," she said, adding that France was being set back €300 million each year.
She said the story of the Navigo pass was "emblematic" of the political management of President Francois Hollande and Prime Minister Manuel Valls.
"They offer gifts to win elections then leave unpaid bills for the French afterwards," she said.
She added that the extra money could improve CCTV, add better security, and create new bus routes.
The Socialist Party said when bringing in the changes that the move was a measure of solidarity between wealthy Paris with the generally poorer suburbs.
“This revolution of a flat-rate pass will help create regional unity, greener travel and boost competitiveness for companies in the Paris region. It will also be a formidable tool to help redistribute spending power,” a statement said.
The current €70 pass marks a big reduction for those living further out, who had to cough up €113 for a ticket covering zones 1 to 5, and €105.40 for a ticket covering zones 1 to 4.