Fears are being raised that the rural school transport scheme won't have enough capacity to carry 120,000 children owing to Covid-19 safety measures.
The Dáil also heard concerns schools will face a "loaves and fishes" scenario in trying to fit children in classrooms while allowing for social distancing.
Sinn Féin TD Donnchadh Ó Laoghaire raised both issues in the Dáil with Education Minister Norma Foley.
Mr Ó Laoghaire claimed parents and schools were "in the dark" over the school transport situation. He asked if 120,000 children would be accommodated on the school transport service this year.
Ms Foley said all school transport services were reviewed over the summer months and some routes may be altered, extended or withdrawn depending on the number of eligible children for the following school year.
She said due to the "exceptional circumstances" she requested the closing date for payment for the service be extended to next Tuesday.
Labour TD Aodhán Ó Ríordáin criticised this extension from the original deadline of today as "insufficient and frankly a joke".
The department last night said the payment deadline date was necessary to allow Bus Éireann adequate time to plan routes and allocate tickets for the new school year and a further extension would result in a significant delay in issuing tickets to families.
In the Dáil, Mr Ó Laoghaire said Ms Foley was not answering whether 120,000 children would be able to avail of school transport in September.
Ms Foley said: "All children who are eligible for school transport and who complete the application and payment process on time will be accommodated... where such services are in operation."
Earlier, Mr Ó Laoghaire asked about classroom space, saying some schools can't reconfigure and "do the act of the loaves and the fishes".
Ms Foley pointed to around €370m in funding being provided to schools as part of the Government's reopening plans as "substantial resources going into schools to facilitate doing what needs to be done".
Separately, Ms Foley is refusing to budge on calls for her to intervene in a row over the withdrawal of school transport for students in Dublin.
Bus services have been pulled for a number of schools and many parents will have to drive children unless they pay private bus operators more than €1,000 per child. Rise TD Paul Murphy called for the services to be reinstated.
In a letter to him, Ms Foley said: "Dublin Bus has confirmed the services referred to were operated by private operators on their behalf and that following a review of the services it was decided not to extend contracts for the new school year."
Schools in Sutton, Tallaght, Templeogue and Greenhills have been told the service will not be in place.
If a song title was to best sum up the reaction to the Government’s roadmap to reopening schools, Elton John’s classic ‘It Ain’t Gonna Be Easy’ would be a top contender.