Since RSU withholding is standardised across the company irrespective of the effective rate different employees pay, should I expect to receive a refund on the overpayment?
You may or may not receive a refund, as your total tax liability for the year is a function of many different factors.
You are correct in drawing a distinction between the amount withheld (or the rate of withholding applied) from any particular transaction and the effective tax rate that results from your entire tax situation at year-end. Taxes withheld, regardless of the source of income, essentially form a single fund of money that is available when you file your tax return, to pay your total tax liability. If the fund is larger that your total tax liability, you receive a refund. If the fund is not enough to pay all your tax liability, you owe money to the IRS.
Refunds are not calculated on the basis of individual transactions (RSUs versus withholding, salary versus payroll withholding, etc.), but on the sum of all your income and deductions for the tax year.
You may or may not receive a refund, as your total tax liability for the year is a function of many different factors.
You are correct in drawing a distinction between the amount withheld (or the rate of withholding applied) from any particular transaction and the effective tax rate that results from your entire tax situation at year-end. Taxes withheld, regardless of the source of income, essentially form a single fund of money that is available when you file your tax return, to pay your total tax liability. If the fund is larger that your total tax liability, you receive a refund. If the fund is not enough to pay all your tax liability, you owe money to the IRS.
Refunds are not calculated on the basis of individual transactions (RSUs versus withholding, salary versus payroll withholding, etc.), but on the sum of all your income and deductions for the tax year.