My husbands company pays him $55.00 per day for per diem when he travels outside of the city. Since he doesn't have to turn in receipts for this, it shows up on his check as taxable wages. Which I understand as it is a nonaccountable expense. However, the net for this $55.00 comes to $35.55 on his check, meaning there are $19.45 worth of taxes, this seems high to me. Is the tax rate for per diem expenses higher than normal wage taxes?
Thank you,

While per diem is not taxed higher, it is possible that the per down pushes him into a higher tax bracket, resulting in higher withholding.