Over-reporting constitutes inaccurate information and requires the IRS to determine the correct information. If you discover that you overwithheld tax under chapter 3 or 4 by March 15 of the following calendar year, you may use the undeposited amount of tax to make any necessary adjustments between you and the recipient of the income. However, if the undeposited amount is not enough to make any adjustments, or if you discover the overwithholding after the entire amount of tax has been deposited, you can use either the reimbursement procedure or the set-off procedure to adjust the overwithholding.
If you discover after March 15 of the following calendar year that you overwithheld tax for the prior year, do not adjust the amount of tax reported on Forms 1042-S (and Form 1042) or on any deposit or payment for that prior year. Do not repay the beneficial owner or payee the amount overwithheld unless you are a withholding agent for the payment that is a QI, WP, WT,or participating FFI that is eligible to file a collective refund on behalf of one or more of its account holders, partners, beneficiaries, or owners (as applicable).