Accidents and injuries represent only about 10 percent of long-term disabilities; diseases, back problems, cancer are more likely to trigger a disability claim. Disability insurance at work rarely will make up for your lost earnings, should disability or death occur.

If your group benefits are typical, then your safety net has a few significant holes.

Coverage usually ends after a year or two. Payments are typically 60 percent of your salary and are taxable; disability insurance paid personally is not taxable. Higher wage earners will encouter maximum monthly limits. It is difficult for people to pay their mortgage and support their family on a 50 percent pay cut.

You can't take it with you. If you lose or leave your job, most employer-provided coverage ceases and you will need to pass a medical to get a personal disability insurance policy. And you won't get a policy without a job.

Group life insurance also lacks portability, while purchase limitations are generally a few times your salary, nowhere near a lifetime of earnings. Here, too, it is important to supplement your workplace coverage.