The estate tax is a one time tax based on the value of the deceased person’s assets as of their date of death. Assets passing to a spouse are not taxed due to the unlimited marital deduction. For the rest of the assets passing to someone other than a spouse, there is an estate tax exemption where the estate is not taxed if the assets are below a certain value.
The federal estate tax exemption is more than 11 million dollars and the New York estate tax exemption is more than five million dollars. So the vast majority of estates do not pay estate tax.