Disability advocates want the Federal Government to work with the nation's biggest businesses to create jobs for disabled Australians, instead of limiting access to the disability support pension (DSP).

The Government has confirmed thousands of people under the age of 35 on the DSP will have their ability to work medically reassessed, in a bid to get more people into the workforce.

The change is part of sweeping changes that the Federal Government is expected to introduce to the welfare system in Tuesday's budget.

The president of People With Disability Australia, Craig Wallace, says the changes will not help disabled people into the workforce because there are no guaranteed jobs.

Mr Wallace says disabled people will instead be forced onto the New Start allowance, which will reduce their standard of living.

"Reassessing people without guaranteed jobs for them to go to will mean that people are going onto the New Start allowance, which around $160 less a week," he said.

"So the result will be those people being homeless, being in poverty, being unable to afford essential equipment - electricity and other items that they need."

Mr Wallace says the Government should be working with the nation's largest businesses to create jobs for disabled people.

"Let's say we go out to the top 40 companies within the ASX 100 and we create 500 jobs each - the Government stumps up to provide the rest and that way we actually get an economic participation outcome for those people as well," he said.

More than 800,000 people currently receive the DSP, a figure that grows by 1,000 every week.

A single person over the age of 21 can claim a maximum of $766 per fortnight on the DSP.

Treasurer Joe Hockey has not said exactly how many people will be reassessed, but there are reports that the figure will be around 30,000.

Social Services Minister Kevin Andrews told the ABC on Friday that many on the disability support pension have the capacity to work, but there is little incentive.

Mr Andrews says it is unfair that many young people on the DSP are capable of working but are not out looking for jobs.

"We think that there should be participation requirements for people under 35, if they're capable of working," he said.

"Obviously, if they are profoundly or severely [disabled] they shouldn't be working but, where there is a capability of working, they should not only have to go along and have an interview, but they should have some search requirements like other young people do."