If insurance proceeds are paid out to the beneficiaries, and the IRS later becomes aware that the benefits were subject to the estate tax: a) the IRS can follow (and attempt to collect) the life insurance proceeds as far as it can trace them b) the IRS may only collect the amount owed from the executor of the estate and any beneficiaries who received payment. c) the insurer may be liable for the tax owed. d) the IRS may only collect the amount owed from the executor of the estate