There is usually a cap on those high interest rates - at my CU, its $25k. They pay 2% though, not 4% - it used to be a pretty good deal, but these days its easy

There is usually a cap on those high interest rates - at my CU, its $25k. They pay 2% though, not 4% - it used to be a pretty good deal, but these days its easy to get a money market fund elsewhere that pays more than that with no maximum.