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Add company max limit of seaman's deduction per month on Global Rate 9.
Enable Seaman's Deduction option on a person under the Constants tab.
Recalculate and check the new calculation of basis for tax withholding. The system prorates the Global Rate 9 value per the number of tax days in the month (W80) and reduces the taxable wage by the found amount.
Example:
When the option is OFF, the taxable wages on a crew are NOK16686. Tax days in month = 9.
Enable option and recalculate. The amount of seaman's deduction should be 4200/30 * 9 = 1260. I.e. taxable wage 16686-1260=15426