You do not sound as a person who handles intricasies of finances on daily basis, this is why you should redirect the qustion to your familyu2019s tax professional who does hte filings for you.The form itself, W-9 form, is a form created and approved by the IRS, if thatu2019s your only inquiry.Whether the form applies to you or to your husbandu2019s estate - thatu2019s something only a person familiar with the situation would tell you about, there is no generic answer to this.