The question of whether plans written under the National Disability Insurance Scheme (NDIS) expire will go to the full Federal Court, in an appeal that advocates say could have implications for participants' ability to challenge agency decisions.

The National Disability Insurance Agency (NDIA) lodged an appeal against a court ruling that required it to reassess the level of funding and support owed to a 13-year-old Aboriginal boy in Tennant Creek.

Late last month the court ruled that the Administrative Appeals Tribunal erred in deciding not to review a $60,000 cut to the boy's plan because it was about to expire.

The court held that plans do not expire or cease to operate when they become due for review, and ordered that the agency reconsider the boy's matter.

A spokesperson for the NDIA said the agency had elected to appeal the decision in order to clarify aspects of the scheme's operation under the act.

If leave to appeal is granted, it will be just the second time the full Federal Court weighs in on the running of the NDIS, according to Shelley Landmark from Northern Territory Legal Aid.

Ms Landmark, who is representing the boy, known legally as SSBV, said the court's decision last month affirmed participants' rights to appeal planning decisions to the tribunal.

"It's really important, particularly in the early stages of the scheme ... that people do have a right to have decisions of the NDIA reviewed by independent bodies," she said.

"We want to make sure that we get the scheme right.

"Certainly from our experience on the ground there are some issues happening at the moment with the roll out of the scheme which does make it really, really vital that people with disability have access to that independent review of decisions."

The NDIA spokesperson said it would be inappropriate to give any further information on its reasons for launching the appeal because the matter is before the court.

"The appeal will not affect SSBV's ongoing reasonable and necessary supports," the spokesperson said.

Tennant Creek teenager 'regressed' with reduced support

The boy at the centre of the case has foetal alcohol spectrum disorder, ADHD, conduct disorder and post-traumatic stress disorder.

His first plan contained $75,615 worth of support in 2015, including funding for up to 15 hours a week of after-school one-on-one support from social workers, which his mother said had made him "a different boy", happier and more engaged.

But the plan was cut to $14,638 early last year, with what the Administrative Appeals Tribunal called "little in the way of explanation".

The boy's mother said that since the reduction in support, the boy had stopped going to school and had gotten in trouble with police, and was facing criminal charges for stealing and property damage.

The tribunal said it was evident the boy had "regressed" in the absence of the earlier support, and said its withdrawal meant that some of the teenager's progress "[had] been thrown away, because the gains made as a result of it were not built upon or consolidated".

Despite deciding it had insufficient time to review the boy's plan before its expiry date, the tribunal stated that: "the applicant urgently needs restoration of supports similar to those that were provided to him during the 2015 plan".

A date for the Federal Court hearing is yet to be set.