Under Section 13 of the 2005 Disability Act, the HSE is required to submit annual reports to outline the ideal timeframe for delivering services and the costs of providing such care.
However, in response to Sinn Féin TD David Cullinane's parliamentary question, the HSE said the last such report was submitted in 2014.
The executive outlined a number of reasons for failing to produce regular reports, saying "converting need identified into a cost, as required, has proven problematic".
The HSE is "working on" the reports from 2015 to 2020, but said this work was being delayed by the HSE cyberattack, which happened last year.
The outdated nature of the IT system is also proving problematic.
"The HSE has prepared and presented Annual Reports for the years 2007 to 2014 to the Department of Health. We are currently working on Reports for the years 2015-2020 to bring us up to date," the HSE response to Mr Cullinane said.
"However, we have experienced delays due to the recent cyberattack and the limitations of the AOS (application object server) Database. It is intended that these reports will be completed by year-end.
"The AOS was developed by a small software development company, which no longer provides maintenance or technical support for the system. The database is 20 years' old and has not had the necessary upgrades or technical changes in recent years that are generally required by IT systems to reflect changes in policy, operational practice and user requirements.
"This has created many challenges for both Disability Services nationally and for system users locally."
AHigh Court judgment last week found that the HSE was falling foul of the law in how it conducts its assessment of need — the process of identifying what services are required for a child with a disability.
"It’s frustrating that the reports are not being given to the minister because these assessments decide resource allocation and that is simply not good enough," Mr Cullinane said.
"These are meant to be annual reports, so the older ones are obsolete. They’re now working on data that is out of date.
For any service using an outdated system is bad, but for one that records the services a disabled child needs, it’s absolutely appalling. There’s no justification for it and we see it across the health system where we don’t have integrated systems across the HSE.
"This is a disgrace that, once again, means that people will have to take cases to court. A better system has to be a priority along with ensuring that the reports which are published are in keeping with the act."
In a statement, the HSE said: "We are committed to developing a new integrated database for Children’s Disability Services. This has been commissioned and it is anticipated that the rollout of it will commence in Q3 2022 and be completed by the end of 2023.