Since it's for emergencies only you may consider allocating your 401k money within said 401k to cash. Most 401k's have a cash portion. My 401k cash option pays 5% interest. Accumulate your 6 months plus 10% penalty plus tax cost. You'll have your emergency money earning tax free interest until and if you must withdraw.If you are in an emergency do you really want to have to hassle with tax penalties from an early withdrawal?