You do not say why his paychecks are being garnished. Are they being garnished for child support or back taxes? TurboTax never knows about offsets to refunds by the IRS or state. You can see if there is an order with the IRS to seize his refund:
https://www.irs.gov/uac/tax-refund-offsets-pay-unpaid-debts
https://ttlc.intuit.com/community/refunds/help/what-is-a-refund-offset/00/26301
Reduced Refund https://www.irs.gov/taxtopics/tc203
NOTE: You can contact the IRS Treasury Offset Program Call Center at 1-800-304-3107 to ask if they have an offset for you on file. TurboTax would not have that information.
https://turbotax.intuit.com/tax-tips/tax-payments/who-can-garnish-an-income-tax-refund/L7cPPzDyc
If you want to file as injured spouse:
INJURED SPOUSE
https://ttlc.intuit.com/questions/1910698-how-do-i-file-form-8379-injured-spouse-allocation