Where to keep emergency funds in a higher rate environment: Savings Acc v CDs v Treasury Bills v Money Market Funds

Note that the rates highlighed below are valid for 10th Dec, 2023.

Safest “can’t lose principle” options

Type Interest Rates (APY %) Post tax effective rates @ 40% Fed, 10% state (APY %) Note
Savings Account 4.35 2.18  
CDs for 1 year 5.2 2.6  
T-Bills 5.2 3.12 No state tax
Federal Money Market funds (Used FDRXX) 5 3  
CA Money Market funds (used FABXX)   2.5 No Fed or CA state tax

For this date and interest rates, it seems that T-Bills provide the highest yield post tax.

Funds with risk based on interest rates

Type Interest Rates (APY %) Post tax effective rates @ 40% Fed, 10% state (APY %) Note
TLT (20+ year treasury ETF) 4.35 2.61 No state tax
SHV (<1 year treasury ETF) 5.17 3.1 No state tax
CMF (CA Muni Fund)   3.17 No Fed or CA state tax
CALY (CA short term)   3.08 No Fed or CA state tax