How Are Social Security Disability (and SSI) Backpayments Calculated?

When you are awarded Social Security or SSI disability benefits, Social Security will owe you more than your monthly disability checks. You'll also receive a check for SSI or SSDI back pay. How much back pay you're owed depends on different factors, including the type of disability benefits you are receiving and how long you were owed past benefits.

Types of Back Payments

Back payments are paid for the months between the date you applied for disability benefits and the date you were approved for benefits. Due to the number of people that are applying for disability benefits and the time it takes to process your application, there is usually a long delay between your disability application date and approval date. But note that, for Social Security Disability Insurance (SSDI) benefits, Social Security has a five-month waiting period, so you're only eligible to receive back pay for any delay beyond the waiting period (see "When Payments Will Begin," below, for further information).

Those who get SSDI back pay will also get payments for the months between when you became disabled (your "disability onset date") and when you applied for Social Security Disability benefits. These are called retroactive benefits, because you can get them even before you applied. These are benefits that you would have received if you had applied for benefits earlier.

SSDI v. SSI Back Pay

The type of back payments you're eligible for depends on the type of benefits you are receiving. Those who are disabled can receive SSDI (benefits for those with enough work history) or SSI (benefits for those who have low income and assets). It's possible for individuals to receive both benefits, so you can receive both SSI and SSDI back pay. Below is a chart telling you what back payments you'll receive if you get approved for both SSI and SSDI.

Note that there is no back pay maximum, either for SSDI or SSI.

When Disability Payments Begin

For those who are receiving SSI benefits, payments begin the first full month after you are approved for benefits. For example, if you are approved for SSI benefits on January 1, you can expect to begin receiving benefits on February 1. There's an exception to this rule for individuals who were determined to be "presumptively disabled." Those individuals can begin to receive benefits while their application is being processed.

For those who are receiving SSDI benefits, several factors affect when your payments begin: your disability onset date, your application date, and the five-month waiting mandatory period for SSDI. (There's one exception to the waiting period for SSDI; claimants who have been diagnosed with ALS don't need to wait five months.)

Disability onset date. Social Security will use the date you filed a disability application as your "alleged onset date." If Social Security doesn't challenge this date, the date of application will become your "established onset date" (EOD). Your EOD is important because it is on that date that benefits can begin.

(Sometimes Social Security changes your alleged onset date to a more recent date so that you'll get less back pay. If you were disabled for a period of time before your application date, you may want to hire an SSDI attorney to help you challenge your established onset date, so that the onset date reflects when you actually became disabled and unable to work.)

Wait period. A mandatory waiting period applies to all SSDI claims. You must be disabled for five months after your disability onset date before you can start receiving SSDI cash payments. You will receive disability benefits starting at the beginning of the sixth month. The five-month wait period is generally shorter than the time it takes for an application to be approved, so the waiting period doesn't usually delay the start of your monthly payments, but it does affect the amount of your SSDI back pay. Since Social Security doesn't pay disability benefits during the waiting period, you won't get paid back payments for the five months of the waiting period).

Application date. You won't be able to collect retroactive benefits generally for more than 12 months—the 12 months before your application date. If you the five months of the waiting period to the 12 months of retroactive benefits, the farthest back that Social Security will recognize a disability onset date is 17 months before the application date (12 + 5 = 17). This is true even if you actually became disabled years ago. Another way to think about it: if you weren't disabled more than five months before your application date, you aren't going to get any retroactive benefits.

Examples of Back Payment Calculations

Your "date of entitlement" is the date that Social Security starts owing you benefits. For SSDI, it's five months after your disability onset date. By using your date your entitlement, you should be able to calculate the amount of your SSDI back pay. Here are some examples using our SSDI back pay calculator.

How Are Back Payments Made

If Social Security approves you for SSDI only, you'll most likely receive one lump-sum payment for the entire amount of your SSDI back pay.

If you're approved for SSI, or you get approved for both SSI and SSDI, the rules are different. Social Security generally pays the past-due benefits for SSI or combined SSI/SSDI in three equal installment payments, separated by six months each. However, you are eligible for larger first and second installments if you need money for "necessities" (housing, food, medical needs) or to pay off debts for necessities. Or, you may be eligible for one lump-sum payment if you are not expected to live past the next 12 months or you are no longer eligible for SSI benefits at the time you receive your back pay (and not expected to become eligible for benefits within the next 12 months). For more information, read our article on lump-sum payments of back pay.

When You'll Receive Your Back Pay

You should receive your SSDI or SSI back pay in a separate check or direct deposit one or two months following your approval. You may receive it before or after you receive your first monthly payment.

To learn more about disability back pay in general, see Disability Secret's section on Social Security disability backpay.