Doctors have been told the hospital will open 11 years after its original deadline.
The National Children’s Hospital is reportedly expected to open in March 2025, according to doctors.
Last September builders Royal BAM said the building was over 70 per cent complete and was due to open in September 2024.
However, paediatricians were recently told the new deadline is March 2025.
According to the Irish Mail on Sunday, senior officials involved in the project expect the deadline to fall back even further.
They said they hope to get patients into the new site at St. James' University Hospital by the end of 2025.
The National Children’s Hospital was first intended to open in 2014, but it has been delayed by controversy over its cost and location throughout the past 11 years.
Public Accounts Committee Chair Catherine Murphy TD told Newstalk a supplementary budget will be needed next year to complete the project.
“The cost of it, I don’t think, will be determined for years,” she said. “We were assured at the Public Accounts Committee that there will be sufficient funding for this year. The amount is a combination of fit out costs on the build costs of the €1.7 billion.”
Previous reports suggested the final cost of the project was expected to be over €2 billion.
Deputy Murphy also said it will not be easy to transfer patients to the new hospital when completed.
“I'm sure that the doctors that are saying that it's likely to be the end of  are probably people who understand the complexity of occupying a hospital,” she said.
“It's not just a question of putting patients into ambulances and moving them from one building to another. I don't know if work is underway to plan for that process at this stage.
“I certainly don't think it will be straightforward.”