In many systems, part of a tax obligation is collected before the final result is known. Withholdings and advance payments distribute compliance during the year or when performing certain operations; they do not always represent the final tax.
Withholding at source
A withholding consists of separating part of a payment and handing it over or declaring it in accordance with the applicable rules. Whoever pays may assume the duty to withhold, while whoever receives the income must recognize it as appropriate. The withholding can function as an advance, as a final payment for certain cases, or with another legally defined scope.
Advance or on-account payments
Some people or activities may be subject to periodic payments calculated on previous results, estimates, or an established base. Payments on account reduce the outstanding balance when the final obligation is calculated, but an incorrect estimate can produce differences that must be regularized.
Reconciliation and receipts
When preparing a closing, it is useful to compare the credited payments with the calculated obligation and keep certificates or proof issued by whoever withheld. Differences can arise due to errors in identification, periods, amounts, or due to payments that were not credited correctly. Reviewing the items before filing a declaration avoids omissions.
Cash flow and forecasting
Advances affect the money available before the final closing. A prudent plan separates the withheld amounts from the funds that actually remain free and considers income variations. Cash received should not be confused with net income after all obligations.
Conclusion
Withholdings and advances are collection and regularization mechanisms, not necessarily an exact measure of the final tax. Their nature, accreditation, and effects depend on local rules.