As residents in a high-tax state (CA), can you think of any reason why it would be stupid or short-sighted to put the majority of our cash, currently held in money market accounts, into 6 month T bills instead? We would, of course, leave sufficient funds in a money market account for a year's worth of living expenses in case of emergency. Since T bills are exempt from state taxes, this seems like a win. Also, the rate of return seems better than putting it in a state-specific tax exempt money market fund.

Am I missing something here?? Thanks in advance.