REHAB and the Central Remedial Clinic have shared in the €3.4m proceeds of a fundraising organisation which offers monthly prize draws.
The profits generated by the Care Trust, which is part-owned by both charities, delivered around €1.7m to each of them last year.
The Care Trust asks members of the public to contribute €15 or more each month to be included in the prize draw. Proceeds go to both disability bodies and the Mater Hospital.
A separate subsidiary of Rehab, the Polio Fellowship of Ireland, has also received more than €500,000 in the last three years in compensation from the Charitable Lotteries Fund.
This is the fund which paid Rehab more than €10m over the same three years to support its lottery, which had card sales of more than €4m but profits of less than €10,000 in a year.
The Polio Fellowship of Ireland was set up in the 1960s and provides day services to people with a disability. Its latest accounts noted the reduction in funding from the Charitable Lotteries Fund, which is being wound down.
It also had cuts in funding from the HSE, ending up with a deficit of €13,758 in 2011.
The different funding streams of Rehab and other charities which are in receipt of public and charity funds is to come under the scrutiny of a second Oireachtas committee. The Joint Oireachtas Committee on Health and Children decided yesterday to write to all these Section 39 organisations in relation to funding and remuneration.
This follows moves by the Dail Committee on Public Accounts to also ask the HSE for a copy of the report it will draw up on salary levels in these organisations. The move by the health committee will put further scrutiny on Rehab chief Angela Kerins, who is refusing to disclose her salary.
Health committee chairman Jerry Buttimer said: "The committee agreed an emergency motion to contact each of the Section 39 organisations to invite them to outline the funding model and breakdown of their different sources of funding.
"They will also be asked to outline the remuneration received by all executive staff and the funding source from which such remuneration is derived in terms of public and private sources or the percentage of each.
"We will also ask the organisations to outline any decline in public support for their fundraising efforts or other supports following revelations about other agencies in recent months.
"We will also be asking the HSE to supply the committee with a detailed evaluation of the situation."
The chairman said he was appealing to the public to continue supporting charities and the very important services they provide to the most vulnerable in society.