Historically critical for married couples to use both spouses' exemptions. Since portability now lets a surviving spouse inherit unused exemption directly, bypass trusts are used less for pure tax reasons — but still useful for creditor protection, remarriage protection, and generation-skipping goals.
Glossary · trusts
Bypass trust (credit-shelter trust)
Also called: credit-shelter trust, A/B trust
In plain English
A trust funded at the first spouse's death with an amount up to the estate-tax exemption, bypassing the surviving spouse's estate.