But more and more people are finding they can't always get what they've paid for -- at least not very easily.
David Elices worked 20 years at the same job; all the time paying Social Security disability insurance.
But last October, he suddenly couldn't work any more. He was having trouble just walking and talking, he couldn't stand up. He was diagnosed with a progressive disease called cerebellar ataxia.
"I've been trying to avoid any assistance as far as help from the government. It is just to the point now where I have to have it because I can't work," said Elices.
Elices applied for Social Security Disability Insurance; it is a benefit that's been around since 1956. It's supposed to protect workers who are permanently injured or sick, and are unable to ever work again.
The exact amount of the benefit is based on the age, earnings and time in the work force. For most people that equals less than $800 a month.
"My expectations were extremely, extremely naïve," said Elices.
Elices' claim was denied. Social Security wanted more of his medical information. Now, he's living off his savings while he appeals and he's one of a growing number of workers trapped in a complicated system that appears to be failing many people who need it most.
"When we finally had to talk to a lawyer they told us that you had to treat Social Security as the enemy," said Elices.
Nearly 240,000 Californians applied for federal disability insurance in the last year. Most of them will be denied. That's because Social Security requires more information and that leads to a lengthy appeals process that could take months, or even years until people see their check.
"I first started having some symptoms in about 1997, just weird things like seeing double," said Rachel Flynn.
Flynn suffers from a neurological disorder.
"They call it a myostetic syndrome because it means that I have muscle weakness. The muscle is fine, the nerves are fine, the muscle receptors are being destroyed by my immune system," said Flynn.
But her requests for Social Security disability insurance have already been denied twice. Her last chance is a hearing later in May.
Did you ever imagine that this process would be so difficult?" asked ABC7's Carolyn Johnson.
"I had no idea, I had no idea. I didn't know it would be so personally difficult filing, but personally and psychologically it was pretty devastating," said Flynn.
Flynn has been waiting two years for approval from Social Security.
Attorneys Nancy McCombs and Georgeana Roussos are the first line of defense for many people struggling to get their disability benefits.
"The system is completely overextended and under-funded," said Roussos.
"People's lives are being ruined because it takes way too long to get their cases approved which means it takes way too long to get money to live on," said McCombs.
"They will eventually sell through everything they have. They will sell their car, they will sell all their resources in order to qualify for general assistance and they will try to survive on that," said Roussos.
Social Security acknowledges it has problems.
"The American people are waiting too long to get their disability benefits," said Lowell Kepke from the Social Security Administration.
Kepke is the regional spokesperson for Social Security. He says shrinking government caused by budget cuts and an aging population is straining the system.
"We have a lot more older people in America, and as they get older they are more prone to getting sick and having conditions that create disability. So our disability workload is increasing," said Kepke.
There is though some relief on the way.
"Congress has given us the funding to hire additional people. Social Security is hiring almost 4,000 new employees nationwide and that will make a big dent," said Kepke.
Social Security began hiring that additional staff earlier this year. They've also streamlined the approval process, so that means people with fatal disabilities like acute leukemia, ALS and pancreatic cancer will get their benefits immediately.
That will help some patients, but not Flynn and Elices, whose conditions are severe, but not fatal. They're still waiting, wondering when and if they'll finally get the benefits they paid for.
"I've had to think about it a lot because I don't feel entitled to it, you know, 'they owe me.' It realistically really is that I can't work, and that's exactly what this system is set up for," said Flynn.
"It's not that Social Security is going to make me rich, it's just going to cover part of the expenses and I don't have that many expenses," said Elices.
Flynn has her hearing on May 20th. Social Security expects to have all of those nearly 4,000 positions filled by the end of May.
Written and produced by Ken Miguel.