A HELOC pays interest-only while the draw period runs, then steps up to repay the whole balance in the years that are left. See what you pay now, what you pay after, and what happens if the rate climbs to its ceiling.
A HELOC has two payments, and the one you are quoted is the smaller one. During the draw period — usually ten years — you owe interest only, so the payment is small and the balance never moves. When the draw period ends the repayment period starts, and that same untouched balance has to be repaid over the years remaining. The payment does not drift upward; it steps.
On a $100,000 balance at 8.5% with a ten-year draw and a twenty-year repayment, interest-only runs about $708 a month and the first repayment payment is about $868 — and it is worse at a higher rate or a shorter repayment period. Put your own numbers in below to see both payments, the multiple between them, and what the payment becomes if Prime rises.
Only the balance you actually carry matters — an unused limit costs nothing but the annual fee.
Variable plans are Prime plus a margin. The lifetime ceiling is 18.00%.
Paying principal during the draw period is the one lever that shrinks the step-up. This is what it does.
| Year | Phase | Rate | Payment | Interest paid | Balance |
|---|
What this is and isn't. Every payment is assumed to arrive on time and every rate change is assumed to apply on the anniversary, which is tidier than reality. The Prime change field moves the rate in a straight line; Prime does not move in straight lines, so use it to test a direction rather than to forecast one. Interest is charged on the balance you actually carry, so if you repay and redraw, your real interest will differ from any single schedule. This is an estimate for comparison, not a quote, an application, or a Truth in Lending disclosure.
Nothing goes wrong to cause the step-up. It is arithmetic. During an interest-only draw period your payment covers the interest and nothing else, so after ten years you owe exactly what you owed at the start. Then the plan gives you the remaining years to repay all of it. A balance that had thirty years of runway now has twenty, and it has to amortise, so the payment has to rise.
Two things make it worse than people expect. The repayment period is usually shorter than the draw period suggests — a ten-year draw followed by a fifteen-year repayment is common, and that compresses the same balance into fewer payments. And the rate is variable, so the step-up arrives at whatever rate exists in ten years, not the one you were quoted.
Only one thing does, and it is available from day one: pay principal during the draw period. Nothing requires you to, which is exactly why most people do not. Put a few hundred a month against the balance and two things happen — the balance that has to amortise is smaller, and the interest you pay in the meantime falls, because interest is charged on the balance you carry rather than on the limit you were approved for. Set the extra principal field above and watch both the step-up multiple and the ending balance move.
Refinancing the line at the end is sometimes offered as the answer. It is a plan that depends on qualifying, on having equity, and on rates ten years from now — three things you do not control. Treat it as an option, not as the plan.
A variable HELOC has a lifetime ceiling, and on the plans modelled here it is 18.00%. That is not a scare number, it is a contract term, and it is the honest upper bound on what the payment can become. The calculator prints it because a payment you could not afford at the ceiling is worth knowing about before you sign, not after. If that figure is uncomfortable, the fixed-rate structure is the alternative — and the crossover calculator prices what that certainty costs.
None of this makes a HELOC a bad product. A small payment while you need one is genuinely useful — bridging a renovation, covering a gap between incomes, holding a line open against something that has not happened yet. The problem is only ever using the interest-only payment as the number you budget against for a decade. Know both payments at the start and the structure works the way it is supposed to.
Speak Straight Mortgage is a mortgage broker; we do not lend. This calculator produces estimates from figures you enter and is not an offer of credit, a commitment to lend, an application, or a Truth in Lending disclosure. Your actual rate, margin, draw period, repayment period and fees are set by the lender and disclosed to you before you accept a plan.
Home equity lines of credit are open-end credit. Where a plan carries a variable rate, the rate is the Prime Rate plus a margin and may increase after opening; the maximum annual percentage rate is 18.00%. Costs to open a plan generally range from $0 to about $1,000 and may include valuation, title, recording and government charges, and on some programs a first-draw fee charged as a percentage of the amount drawn and financed into the balance. An annual fee may apply. Fixed-rate equity lines are also available, so not every plan is variable. Equal Housing Opportunity.
Send us the plan you have been offered and we will tell you what the step-up looks like on your balance, and whether a fixed structure costs less over the years you actually intend to carry it. No credit pull to start.