If someone receives SSDI (backpay) are we required to file taxes on it?

[HelenaC]

You might need to pay taxes on a small portion of your lump-sum payment. However, you might be able to avoid these taxes by apportioning prior year benefits to those previous years’ income (without filing any amended returns).  

Please see the following link on how to enter your Social Security Disability income: Where do I enter an SSA-1099, SSA-1099-SM, or SSA-1099-R-OP1?

After you enter your lump-sum Social Security payment information, TurboTax will automatically figure what if any taxes you owe due to the lump-sum payment.   

Do not report your dependents SSA-1099 income on your income tax return . Your child or other dependent would report their SSA-1099 on their own return, but only if they make enough income to be required to file (this is uncommon). If Social Security is your dependent's only income, they most likely don't need to file a return.

Related information:

 What is a lump-sum Social Security payment?