Parents of an Adult Child With an Intellectual Disability

Written by Richard O'Shea, Solicitor TEP · Mary Molloy Solicitors, established 1981 · Last reviewed 21 August 2026

Eighteen changes everything — and nothing

Nothing about your child changed on their birthday, but their legal position did: they're an adult, presumed to have capacity, whose decisions are their own unless the functional test shows otherwise — decision by decision. Parents have no automatic authority over an adult child, which surprises families at the first bank account, medical consent or service agreement. The Act's answer isn't parental control restored; it's support arranged at the right tier, in the adult's own name.

Matching support to your child

• Many adults with intellectual disabilities decide well with help — an assistance agreement naming a parent formalises the help without taking the decisions
• Where deciding is genuinely joint, a co-decision-making agreement gives it legal standing — commonly for money and service decisions
• Where certain decisions can't be made even with support, a DMR appointment — typically a parent — covers those specified decisions, no more; the courts take particular care that young adults keep every decision they can hold
• Capacity varies by domain — an adult may hold decisions about daily life and need representation only for property or medical matters; the arrangement should match that map, not flatten it

Money, services and the practical layer

The recurring flashpoints: disability allowance and accounts (whose name, who operates, what authority the institution accepts); consent for medical and service decisions; and service agreements with providers. Right-sized arrangements answer each — and prevent the informal workarounds that unravel at a staff change. Where a personal injury award or inheritance is in the picture, structures need particular care; take advice before funds land.

The question behind every other: after us

Succession planning here is its own discipline: wills that provide without wrecking means-tested entitlements (discretionary trust structures are the standard tool), a chosen and briefed next generation of supporters, letters of wishes that transmit what only parents know, and arrangements reviewed as everyone ages. This is where Richard's TEP background does its heaviest lifting — estate planning and capacity law are one subject in these families. The drafting sits with our main practice; the planning conversation starts here: 01 5827148.