Can my portion of an inheritance be legally withheld from me until I furnish the executrix with my social security number?

Providing the executrix with one's social security number for estate purposes is typically required of all beneficiaries for potential tax issues when one is a beneficiary under a Will or trust. However, for the executrix to withhold a portion of one's inheritance until that beneficiary provides the executrix with his or her social security number is ordinarily not allowed under the laws of all states in this country. You are to get your distribution whether you provide your social security number or not to the executrix.

If there is a possible tax issue and the reason for the social security number is to allow for a distribution of all assets to the estate's beneficiaries by the executor knowing that the beneficiaries may have to pay the government taxes for the estate out of their own distribution, the prudent thing is to hold back so much of the estate's liquid assets until there is a tax clearance for estate tax reasons.

Having the social security numbers of the beneficiares of the estate is normal and often required for reporting purposes.  The executrix of an estate has a fiduciary responsibility and has reporting not only to the court but to the IRS and the state to do.  So yes, give it to her. Good luck.