Should I count an available HELOC or credit card as part of my emergency plan?

A line of credit can be a useful backup layer, but it is not a substitute for cash. Credit lines can be reduced or frozen by the lender exactly when the economy sours and you need them most, and borrowing turns an emergency into interest-bearing debt. Treat cash savings as your first line of defense and a HELOC or credit card as a secondary backstop for a truly extreme, prolonged crisis. It is reasonable to keep a slightly smaller cash fund if you have a large, stable HELOC and low risk of needing it, but do not let the credit line lull you into skipping the cash cushion. The safest structure is a solid cash fund first, with credit as a rarely-used emergency backup behind it.