According to the Social Security Administration, you should apply for disability benefits as soon as you become disabled. So if you're still working, or you've found a job that you may be able to perform while disabled, you can still work while applying for disability. However, there are certain restrictions on how much you may earn while receiving government assistance.
If You're Already Working
The purpose of disability benefits is to provide income to people who are unable to work at all, or to work enough to make ends meet, due to a new or existing disability. This includes a variety of both physical and mental health conditions, and it's determined on a case-by-case basis. So if your medical condition doesn't impact your ability to do your current job, there's a chance you won't qualify for government assistance.
If You're Already Receiving Benefits
If you're renewing a disability claim and considering starting a job, you can absolutely go back to work and continue receiving benefits. This is called a "trial work period," a nine-month period in which you receive your full disability benefit regardless of how much you earn at work. The SSA also provides access to training and rehabilitation to assist you in finding and keeping work. If your work status changes at any time while you're receiving benefits -- whether your hours increase, decrease or you lose your job -- you must report this change to the Social Security Administration.
Qualifying for Disability Benefits
As of 2013, if you are blind, you may earn up to $1,740 a month and still receive disability benefits. If you are not blind, you may earn up to $1,040 a month. Your disability must be something that will last at least a year or result in death -- meaning a temporary illness or injury won't qualify. You must also have worked long enough to qualify for aid from Social Security: depending on your age, this ranges from 1.5 years to 9.5 years of work on which you paid Social Security taxes.
Other Disability Benefits
If you don't qualify for disability benefits, you may still be able to obtain other assistance. If you are low-income, you may qualify for Supplemental Security Income (SSI), which is available to disabled people, and non-disabled people over age 65. Government health insurance (Medicare and Medicaid) is available to anyone whose income falls under a certain limit. According to USA.gov, The Affordable Care Act will make it possible for anyone to find reasonably priced care through their state's Healthcare Marketplace beginning October 1, 2013.