The city promised discounted subway and bus fares to its poorest citizens six months ago, but just days before the Fair Fares program is supposed to launch, the de Blasio administration still doesn’t seem to have a clue how it will be implemented.

MTA board member David Jones has tried several times in the past month to get an answer from the city on when the details of the program will be released, but the city has stonewalled him, he told The Post.

Meanwhile, when a reporter called the MTA’s 511 hot line Friday, the operator knew nothing about the program.

“They made a commitment to offer New Yorkers half fares, but it doesn’t seem like this is going to launch in January,” said Jones, who has been a longtime champion of the plan.

In June, Mayor de Blasio and City Council Speaker Corey Johnson reached an agreement to pay for half-priced MTA fares for the poorest New Yorkers — those who make less than $24,000 for a family of four.

The city allocated $106 million to fund the first six months of the program.

Jones said he expects about 800,000 New Yorkers to take advantage of the program.

City hall officials refused to answer several questions about where New Yorkers will be able to sign up and what the application process will be, even though de Blasio said on the radio Friday morning that his office is working on it.