Section 16: WITHHOLDING OF PERSONAL INCOME TAX FOR NON-RESIDENTS
In general, the calculation requires the non-resident to calculate his/her tax as if he/she were a resident and then to multiply that tax by a fraction, the numerator of which is his/her Delaware source income (with Delaware modifications) and the denominator of which is his/her federal adjusted gross income (with Delaware modifications). The numerator is not adjusted for the Delaware pension exclusion as pension income is excluded by statute from the definition of a non-resident's Delaware source income.
The change in the tax calculation for non-residents requires that, in order it properly estimate annual tax liabilities, non-residents review the Delaware W-4's submitted to their employers. Form W-4NR, Non-Resident Withholding Computation Worksheet, is available to perform the calculation.