A more thorough explanation:

The rule against accumulations is a legal principle that states that any direction to accumulate income from property can only be valid if it is limited to the perpetuity period. This means that the income must be distributed to certain beneficiaries within a certain time frame.

For example, if a person leaves a will that directs their property to be held in trust for their grandchildren until they reach the age of 25, this direction would be valid under the rule against accumulations. However, if the will directed that the property be held in trust for the grandchildren for 50 years, this direction would be invalid because it exceeds the perpetuity period.

The rule against accumulations is closely related to the rule against perpetuities, which limits the time period during which property can be controlled by a trust or other legal instrument. Both rules are designed to prevent property from being tied up for too long and to ensure that it can be used for the benefit of future generations.