Most trust discussions focus on who controls the trust, but a deeper question is how long the trust can legally last. The common-law Rule Against Perpetuities (RAP) historically limited trusts to lives in being plus 21 years, preventing dynastic wealth lockups. Many U.S. states have abolished or extended RAP, enabling dynasty trusts that can last 500–1,000 years.

Duration affects tax, creditor, and control outcomes:

Short-term trust (e.g., 10-year term certain): simple, predictable, often used for income shifting.
Lifetime trust: ends at beneficiary's death, common in revocable living trusts.
Dynasty trust: multi-generational, may avoid estate tax at each generation if drafted correctly.

Jurisdiction	Typical Max Duration	Key Feature
Traditional common law	Life + 21 years	RAP applies
Delaware	Perpetual (RAP abolished)	Dynasty trust friendly
South Dakota	Perpetual	No state income tax on trusts
England & Wales	125 years (Perpetuities Act 1964)	Statutory cap