Childcare vouchers wrongly deducted from SMP

Giggidy

Hi

I am currently on maternity leave since May, before I went on leave, I discussed with HR that my childcare vouchers would continue to be paid by my employer and not deducted from my SMP, as per HMRC's guidelines.

Everything has been going smoothly until my latest payslip where my employer deducted £243 from my SMP for childcare vouchers (that's the amount that used to be deducted from my salary prior to maternity leave).

I queried this with HR and was told that £191 will be refunded to my bank account as they obviously made an error. I was confused as to why I wasn't getting the full £243 as this was the amount wrongly deducted. They came back with this statement:

"..Childcare vouchers are deducted from Gross pay (as a salary sacrifice) and tax and NI is paid on the remainder of salary, so the net cost to you for the £243 of vouchers you receive is less, i.e. £191 so when we refunded the £243 to you in your gross pay, you pay tax and NI on that and so therefore the refund is the net amount £191.."

My pay for August was £697.90 (gross) + £92.60 tax rebate, they deducted £243 CV + £5.09 pension. So I really don't understand why I am being refunded £52.00 less, how can that much be for NI and Tax?