Credit shelter trusts allow married couples to avoid the hassles of estate taxes when passing their assets to heirs. The trust contains a set amount of assets determined by the current IRS laws at the time it was set up and upon the death of the owner the assets of the trust are transferred to the beneficiaries. However, if one spouse is surviving, that spouse maintains the right to the assets in the trust during the remainder of their life. Each couple in the marriage is allowed to use their full estate tax exemption which allows the estate to effectively double the amount exempted. Credit shelter trusts are an excellent way to avoid high estate taxes that would have otherwise affected the estate's funds.