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10-Year Draw, 20-Year Repayment HELOC
The most common HELOC structure in the US: 10 years of flexible interest-only draws followed by 20 years of amortizing repayment. This page walks through the math, the payment-shock transition, and how to model the 30-year cash-flow path for any line size.
The two-phase mechanics
The 10/20 HELOC is structurally a two-phase loan. Phase one, the draw period, runs from the origination date for exactly 120 months. During this phase the borrower can draw against the credit line at will (up to the approved limit), and the only required monthly payment is the interest on the current balance. The balance can rise as new draws hit and fall as the borrower pays beyond the minimum. The minimum payment formula is balance times rate divided by 12, recalculated every billing cycle to reflect the current balance and the current variable rate (typically prime plus margin, updated within one billing cycle of any prime-rate change).
Phase two, the repayment period, begins on the 120-month anniversary of origination. The lender freezes new draws and recalculates the monthly payment to fully amortize the outstanding balance over the 240-month repayment period. The formula is the standard mortgage amortization formula, applied to the balance at the transition date and the rate in effect at the transition date. The rate continues to vary with prime throughout the repayment period, so the payment can change with rate movements; some lenders re-amortize annually to keep the term fixed at 240 months, while others adjust the payment month-by-month to track the variable rate exactly. Read your disclosure carefully to know which method your lender uses.
The CFPB's consumer guidance on HELOCshighlights the payment-shock transition as the single most-misunderstood aspect of the 10/20 product. Survey data suggests fewer than 30% of HELOC borrowers can accurately describe what happens to their payment when the draw period ends, which means the majority encounter the higher amortizing payment as a surprise. The Reg Z 1026.40 disclosure is supposed to prevent this with mandatory payment-example disclosures at application, but the format and timing of that disclosure (often buried in a stack of closing documents) limits its effectiveness.
Payment shock by line size at 7.02% (full draw)
| Line size | Draw (IO) | 20-yr repayment | Shock ($) | Shock (%) |
|---|---|---|---|---|
| $25,000 | $146 | $194 | +$48 | +33% |
| $50,000 | $293 | $388 | +$95 | +32% |
| $100,000 | $585 | $776 | +$191 | +33% |
| $150,000 | $878 | $1,164 | +$286 | +33% |
| $200,000 | $1,170 | $1,552 | +$382 | +33% |
| $250,000 | $1,463 | $1,939 | +$476 | +33% |
| $500,000 | $2,925 | $3,878 | +$953 | +33% |
Payment shock is consistent at roughly 33% across all line sizes at 7.02%. It varies with the rate at the transition date: at 6.00% the shock is ~43%, at 9.00% it is ~20%, because higher rates push the interest-only payment closer to the amortizing payment.
Reducing the shock during the draw period
The most effective strategy to reduce payment shock is to pay additional principal during the draw period. Every dollar of principal paid reduces the balance that enters amortization, which proportionally reduces the amortizing payment. On a $100,000 balance, paying an extra $200 per month during the draw period reduces the balance entering repayment from $100,000 to $66,400 over 120 months. The amortizing payment at 7.02% on $66,400 over 20 years is $515 per month, a $261 reduction from the full-balance $776 payment. The shock from the $585 draw-period payment to the $515 reduced repayment payment is now actually a $70 per month decrease, not an increase.
A related strategy is to time large principal pay-downs near the end of the draw period when a windfall allows. A $25,000 lump-sum payment in year 9 reduces a $100,000 balance to $75,000 entering repayment, cutting the amortizing payment to $582 per month, essentially eliminating the shock. The lump-sum approach is operationally cleaner than monthly extra payments and works particularly well for borrowers with bonus-based or variable income.
A third strategy is to refinance the HELOC into a fixed home equity loan or new HELOC just before the draw period ends. This works mathematically only if rates have fallen since origination; if rates have risen, the refinance creates a higher interest cost than simply transitioning into amortization on the existing line. The refinance path also re-incurs origination costs, appraisal fees, and title work, which on a $100,000 balance can run $1,500 to $3,000 depending on the lender and state. Compare the total cost of refinancing against the natural transition before committing.
When 10/20 is the right structure
The 10/20 structure is the right choice for borrowers who want flexible draws over an extended period (renovation phases, ADU construction, ongoing emergency reserve) combined with manageable monthly payments throughout. It is the wrong choice for borrowers who plan to draw the full line immediately for a known one-time expense; for that use case, a fixed home equity loan with a 10 or 15-year term provides payment certainty and locks the rate at origination. It is also the wrong choice for borrowers who anticipate selling the home in fewer than 10 years; in that case, a shorter-term product or a cash-out refinance built into the next purchase mortgage is typically cleaner.
The 10/20 structure interacts in a specific way with the home-improvement use case. If the renovation is phased over 3 to 5 years (kitchen one year, bathroom the next, exterior the third), the 10-year draw window gives substantial flexibility to time draws against contractor invoices. If the renovation is a single 6 to 18 month project, the long draw window is essentially unused after construction completes, and the borrower is paying for optionality that has no further value. In that scenario, refinancing the HELOC into a fixed loan after construction completes can lock in current rates and accelerate principal pay-down.
For debt-consolidation borrowers, the 10/20 structure is operationally appealing (low minimum payments give cash-flow breathing room while the borrower regains financial footing) but mathematically risky (the 10-year draw at minimum payments means no principal reduction unless the borrower disciplines themselves to pay more). The disciplined consolidator pays the amortizing-payment equivalent ($776 per month on $100,000 from day one) rather than the minimum interest-only payment, which retires the consolidated debt in 20 years and saves a substantial chunk of lifetime interest.
Frequently asked questions
Why do most US HELOCs use the 10-year draw, 20-year repayment structure?
The 10/20 structure is the legacy product design from the 1990s expansion of consumer home equity lending. It gives borrowers a decade of flexible borrowing and minimum payments, then spreads repayment over a long enough period that the amortizing payment is not crippling. Newer products (5/15, 5/10, all-fixed) have emerged but the 10/20 remains the default at Bank of America, US Bank, Citizens, PNC, Truist, and most credit unions.
What is the payment shock on a 10/20 HELOC?
At a fully drawn $100,000 balance and 7.02% rate, the draw payment is $585 per month interest only, jumping to $776 per month amortizing in year 11. The shock is $191 per month (33%). At $200,000 balance the shock is $382 per month, at $50,000 it is $95 per month. Borrowers who add principal during the draw period reduce both the balance entering repayment and the amortizing payment, materially shrinking the shock.
When does the repayment period actually start?
Exactly 10 years from the origination date, regardless of how much you have drawn. The lender freezes the line on the anniversary of closing, calculates the outstanding balance, and recalculates the payment to amortize the balance over 240 months. Some lenders mail a payment-change notice 60 to 90 days before the transition; others change the payment with no warning beyond the original disclosure.
Can I extend the draw period?
Usually no. The 10-year draw is contractual and ends on schedule. Some lenders offer a refinance or extension product (closing on a new HELOC just before the old one's draw ends), but this is treated as a new loan and requires re-qualification: new appraisal, new income verification, new credit pull, new closing costs. Plan for the draw end rather than relying on extension.
How does the 10/20 structure compare to a fixed home equity loan?
A 20-year fixed home equity loan at 7.5% (typical 2026 rate) costs about $806 per month per $100,000 borrowed, with the payment fixed for the entire 20 years. A 10/20 HELOC at 7.02% gives 10 years of $585 interest-only payments followed by 10 to 20 years of $776 to $1,162 amortizing payments depending on the repayment term. The HELOC wins for the first 10 years on cash flow; the fixed loan wins on payment certainty and on lifetime interest if rates rise.
What is the typical lifetime interest on a 10/20 HELOC?
Holding $100,000 balance at 7.02% throughout the 10-year draw generates $70,200 in draw-phase interest. The 20-year repayment at the same rate adds $86,300 in repayment-phase interest. Total lifetime interest: $156,500 across 30 years. Paying down principal during the draw period dramatically reduces both halves of this number.