The base increase resets the base value of the assessed legacy asset for tax purposes.
The base value for heirs is raised to the market value of the asset at the date of death of the previous owner, which reduces future capital gains taxes.
Residents of states with joint property laws or persons holding assets in joint property trusts are eligible for an increase in the right to joint property for a surviving spouse.
Because the benefits of a phased basis go mostly to the richest households, opponents have tried in recent years to limit or eliminate this provision, but without success.