People applying for a particular benefit will, from 2013, undergo tough new medical assessments to "reduce dependency and promote work". Sounds reasonable, you may think, but the benefit in question is disability living allowance (DLA). DLA is not an out-of-work benefit. Nor is it means-tested. This is because DLA contributes to the extra costs faced by disabled people, and the minimum wage does not rise just because everyday life is more expensive. Nor do poverty thresholds or income-tax brackets.

This is where DLA comes in. For example, one of the qualifying criteria for the lowest rate is if you cannot prepare a cooked main meal while alone. This may be due to a mental health condition, or a physical disability. Those of us in this category include epileptics and people with sleep disorders. I can't cook hot food while alone in the house because I may fall asleep and burn it down. Experience shows I can sleep through fire evacuations.

This is just one example of the many ways in which disabled people may qualify for DLA. But as Richard Exell writes on the TUC's informal public policy blog, George Osborne seems confused about DLA's nature and purpose: "Making it harder for disabled people to qualify for it will do nothing to improve – or worsen – incentives to work … disabled people will be paying the price for deficit reduction."

Claiming DLA isn't easy, whatever you may have read. The initial form is 59 pages long. Around half of all claims are refused. In 2008-09, 49% of appeals were turned down, rising to 57% for cases reaching an appeal hearing. The initial application and reassessment procedures are already a bureaucratic struggle for many. When you consider that current estimates put the number of disabled people in this country at around 11 million, while the labour force survey says 40% of people with work-limiting disabilities are in paid employment, 2.9 million DLA claimants doesn't sound quite so high.

But the same coalition that talked about disability and social care in terms of "dignity" and "respect" doesn't see it that way. The Treasury complains that DLA claimant numbers have tripled since 1992. If the total number of disabled people in the UK had risen at this rate, it would be a matter for more than just the budget. But there are other reasons why claimant numbers are up, including increased awareness of DLA's existence. Disabled people aren't always told that they are eligible for help. Often, we're just told what we can't do.

If you want to be misled about the nature and purpose of DLA, look no further than the government's state of the nation report on poverty, worklessness and welfare dependency in the UK, released on 3 June. "There is a high degree of persistence among claimants of many low-income and out-of-work benefits", it says. "For example … around 2.2 million people, including 1.1 million people of working age, have been claiming disability living allowance for over five years".

This statement completely ignores the fact that DLA is not, and has never been, a low-income or out-of-work benefit. And if DLA claimants are "persistent", it is because disability is, by its very nature, "persistent", and citing the fact that people with "substantial and long-term" impairments still have them after five years as an example of persistent welfare dependency is disingenuous and spiteful.

As Rich Watts, director of the Essex Coalition of Disabled People, points out on his Arbitrary Constant blog, the report doesn't bother to define what DLA is for, although it does say 20% of DLA claimants are in the top 40% of income distribution, when DLA is included as income and – here's the really important bit – no account is taken of the extra costs of disability. "DLA is designed precisely to take account of the extra costs of disability/impairment," he writes. But for how much longer?