Breakdown of the withholding and of the non-resident's own tax
Withholding basethe gross, article 31.2
€100,000.00
Payer's withholding
€19,000.00
Payee's tax baseless expenses, article 24.2
€40,000.00
Payee's actual tax
€7,600.00
Excess reclaimable on form 210
€11,400.00
Net the payee receives
€81,000.00
Article 31.3 says the person obliged to withhold «shall assume the obligation to pay the amount into the Treasury, and failure to comply with the former obligation shall not excuse them from the latter»: forgetting to withhold does not save the money.
Article 31.2 forbids the payer from deducting those expenses, even though the payee can deduct them in their own return. The excess is recovered on form 210, not here.
Adjustments: article 24.2 expenses and treaty rate
Personnel, materials and supplies on a job: they shrink the payee's tax and NOT the withholding.