Three-Year Rule

What Does Three-Year Rule Mean?
Section 2035 of the tax code, which stipulates that assets that have been gifted through an ownership transfer, or assets for which the original owner has relinquished power, are to be included in the gross value of the original owner's estate if the transfer took place within three years of his or her death. If gifted assets do not meet the necessary requirements, the value of the assets is added to the value of the estate at the time of  the original owner's death, increasing its value and the estate taxes imposed on it.

Investopedia explains Three-Year Rule
This rule prevents individuals from gifting assets to their descendants or other parties once death is imminent in an attempt to avoid estate taxes. The rule does not include all assets gifted or transferred in that three-year period and is mainly focused on insurance policies or assets in which the deceased retains an interest.