How a HELOC works

PhaseTypical lengthPayment
Draw period5 to 10 yearsInterest only on what you borrowed (often)
Repayment period10 to 20 yearsPrincipal and interest; the payment jumps

The maximum line is your home's value times the lender's combined LTV limit, minus your first mortgage balance. Lenders also check credit score, income and debt-to-income. Compare a HELOC with a cash-out refinance before you choose.