More than 37 million Americans -- about 12% of the total population -- are classified as disabled, according to the U.S. Census Bureau. While disability insurance coverage helps many people keep their heads above water until they can go back to work, those suffering from a more severe and ongoing disability have to turn elsewhere for a financial life raft.

That's where the Social Security Administration comes in. Its disability insurance program (SSDI) provides much-needed income for people with severe ongoing disabilities ... as long as they qualify for benefits.

Brace yourself: one-third of disability applications are denied
Since 1999 the number of applications for SSDI has more than doubled. But so, too, has the percentage of claims that are denied.

In 1999 more than half of applications were approved. Last year, only one-third were. 

Source: Dan Caplinger, The Motley Fool, based on Social Security Administration data

With the odds becoming increasingly stacked against disability applicants, it's more important than ever to ensure that your claim conforms to all of the rules and that you provide all of the information in the right format to speed your application through the gauntlet.

Remember, no one besides you has a bigger incentive to make sure that your application is approved.

DENIED stamp in red ink

Image source: Getty Images.

8 Social Security disability application mistakes to avoid
At the Social Security website are directions on applying online for disability benefits. Everything you need is there. (Although some rah-rah aphorisms and a gift-card code for a free bottomless cup of coffee would make a thoughtful addition.)

Take a stroll through the information at SSA.gov so you know what to expect. What you don't want to do is approach the application process halfheartedly, get stuck, give up, or turn in half-finished homework. While the hoops are plentiful and the requirements intimidating, it's up to you to claim what is rightfully yours.

As you start gathering your paperwork and filling out forms, keep in mind the things that tend to get Social Security disability benefits applications denied. Your claim will be rejected if:

1. You don't have enough "working credits" to qualify.
There's a minimum amount of time you must have worked in the past to qualify for Social Security disability benefits. The SSA calculates your credits based on your age, the number of years you've worked (and therefore paid into the SS system), and when you became disabled. For example, if you became disabled before age 28, you will generally have to have 1.5 years of work before then to qualify. The older you are and the more you've worked in recent years, the better likelihood you have of getting approved.

2. You make too much money.
Do you draw any income from your investments or a trust? Do you receive any workers' compensation money? Your monthly earnings are another factor the SSA reviews when you apply. For 2015 your earnings must average less than $1,090 a month ($1,820 a month if you're blind) to even be in the running to receive benefits. Here it is also important to understand that if you apply for unemployment benefits while you await a decision about your Social Security benefits, the SSA may factor that into their decision, and you may even have to pay that money back to the state.

3. Your condition isn't considered a "disability" under the Social Security Administration's strict guidelines.
To qualify for disability benefits your situation has to be severe: The impairment must have lasted (or be expected to last) for at least 12 months, or be dire enough that it is expected to result in your death. On top of that, your condition must be on the SSA's listing of impairments. (Though you are not automatically disqualified from receiving benefits if your condition isn't listed; that just means you'll have to provide more details for the SSA to evaluate your particular impairment.)

If you haven't received treatment for your condition or if the SSA needs more information than what you provided, they may request that you get a special examination at the SSA's expense.

4. The SSA determines that you are fit to do a different but related job.
If you are still able to do some sort of work -- even if it's not the same work you did before -- your application will be rejected. An examiner will make a determination about your ability to work. But, here again, during the application process it's up to you to establish how your disability leaves you with no options -- that because of the severity of your disability you are unable to do any kind of work-related activities.

This will be based on your employment history and details about the scope of your work. Because this part of the application process plays such a large role in determining your eligibility, do the up-front work of gathering work records before you apply.

5. You didn't have the right documents on hand.
A good filing system is a savior in situations like this. That's because you're going to need to produce a ton of documents about your income, work history, applications for other disability benefits, your medical history, and more. We're talking about a pretty exhaustive list that includes (and is absolutely not limited to):

  • A list of jobs you had (including dates of employment) during the 15 years prior to your disability.
  • Pay stubs, award letters, settlement agreements, and anything else that offers proof of temporary or permanent workers' compensation benefits.
  • An accounting of workers' compensation, state or local government disability insurance, or military disability benefits -- not including Veterans' Administration (VA) benefits -- you have or intend to file for.
  • Details of your injury or medical condition (including names, addresses, dates of treatment, patient IDs assigned to) for all doctors, hospitals and clinics you visited.
  • Dates, test results, and information about the doctor who sent you for any medical tests you've had.
  • Names of medicines you take and the doctor who prescribed them.

6. Incomplete or inaccurate explanations.
Being thorough and honest about your situation is key. Gathering medical records can be an onerous task, especially since it may involve various doctors, hospitals, and other healthcare providers. So review, organize, and provide a thorough accounting of your disability so that the SSA can process your claim efficiently.

If you don't have these records the SSA will contact the medical sources you list. The SSA website says to go ahead and submit what you have (and provide the names/contact information for medical providers that they can contact) and they'll obtain evidence for you. Just keep in mind that adds another layer of due diligence on their end, so if you can easily get the required documentation yourself, do so.

7. A simple technical error.
Remember, a living, breathing person is going to review your application. Mistakes happen. And you, also a living, breathing person, are fallible as well. Little things can slow down your application's review. For example:

  • Photocopies are acceptable for W-2s, tax returns, and medical documents. But in some cases the SSA requires that you mail (or bring into a local Social Security office) the original version of some documents, like your birth certificate. Originals will be returned to you.
  • Any documents you mail must include your Social Security number. Provide that information on a separate sheet, because ...
  • The SSA rules stipulate that you should not write anything (including your Social Security number) on original documents or, obviously, alter them in any way.

What you want to avoid is waiting for someone from the SSA to contact you for clarification. This just prolongs the application process and delays the time it takes for you to start receiving benefits.

8. You decided to just give up.
Patience is a requirement for anyone applying for Social Security disability benefits. Depending on the amount of verification, follow-up, and additional exams the SSA and you have to go through, the process could take as long as a year or more to be approved (although certain conditions like advanced cancers and kidney diseases get sped through the approval process). That's why making sure your application is A-plus work the first time is so worthwhile.

If your disability benefits application is denied, you can appeal the decision. For most people the process of applying is daunting enough. After getting rejected, just giving up may seem preferable to enduring a multiple-step rigmarole appeals process.

But if that's what it takes, that's what you must do as you double- and triple-check to make sure everything's in order for the next go-round. And, of course, submit the correct form to appeal a denied Social Security disability offline or submit an appeal online. You may also want to consider having someone represent you -- an advocate, attorney or third-party representative -- to help with appeals requests or even your original application for disability benefits.

Hang in there, it's worth it
Don't get discouraged. If you're eligible for Social Security disability benefits, your patience will pay off and hopefully help ease the financial burden of being unable to work. You can increase the odds of getting approved if you know the rules and are armed with the right information to make your case.