What if employee salary is very small, say 6000 GBP, less than personal allowance (9440 GBP). Employer has already deducted income tax at source.
After computation, income tax payable would be negative. Will HMRC return to employee paid by employer tax?
Yes HMR will reimburse
The personal allowance is to deduct from the income received during a year and charge income tax thereafter.
If the salary is say GBP 6,000 (going by your example), the relief will be deducted i.e. 6,000-9,440=-3440. But the taxable income cannot be a negative and therefore will be NIL. And therefore also income tax is NIL.
HMRC cannot refund the person.