Box D is on the top left of your W2 form. Form W2 wage statement Box D isa Control Number field. It is usually located below the Employers Name andAddress on the top left side of your W2 form.The Box D Control Number is a code that identifies your unique W2 form inyour employers records. This number is assigned by the companys payrollprocessing software. Please note that not all W2s or employers will include a Box D number.The actual number itself is completely irrelevant to completing your taxreturnHope this is helpful.