Two factors are considered when determining how many months of back benefits a person is entitled to. The first factor is the date you submitted your application for benefits. The second is your onset date (OD), or the date that the SSA determines your disability began. If you qualify for SSD, you can receive back benefits for up to 12 months prior to the date you submitted your initial application or back to your OD, depending upon whether or not your OD fell within that 12 month period. If you qualify for SSI, you can only get back benefits back to the date of your initial application. If the SSA finds that your OD was after your application was already submitted, then your back benefits would only be paid back to the OD. With that said, there are a few other factors that come into play. First, if you filed a previous application, you may be able to use that filing as what is called a “protective filing”. This gets rather complicated, but it can be done. Second, if you qualify for SSD, you will face a 5 month waiting period. In most situations, you will have 5 months of benefits removed from the start of your back benefit period, meaning entitlement really does not start until 5 months after your OD. This waiting period does not apply to SSI benefits. Third, if you qualify for SSD, you will get your back benefits paid in one nice lump sum. If you qualify for SSI, you will not receive your back benefits in a lump sum; instead you will be paid small amounts of back pay (usually under $2000) periodically until they are paid in full.