An irrevocable trust that is used to freeze some assets of an individual for estate tax, not income tax. This estate planning tool is created as a grantor trust to make sure the individual continues to settle his income taxes because income tax laws won’t count or consider the assets that have been taken away from the individual.

However, for estate tax, the worth of the grantor’s estate is lessened by the amount of the asset transfer. The individual will "sell" assets to the trust in return for a promissory note up to certain length, such as 10 years or 15 years. That note will pay sufficient interest to categorize the trust as above market, but the value of underlying assets are awaited to increase at a faster pace.