Interest-Only Mortgages: Pros and Cons

An interest-only mortgage lets you pay only the interest for the first 5-10 years. Your principal balance stays exactly the same during that period. After the IO period ends, you start paying principal too — and your payment jumps.

How it works

Example: $400k loan at 6.5%.

• Standard payment: $2,528/month (principal + interest).
• Interest-only payment: $2,167/month (interest only).
• Savings: $361/month for the first 10 years.
• After year 10: Payment jumps to ~$2,840/month for the remaining 20 years.

The pros

• Lower monthly payment during IO period. Frees up cash for other investments, business expenses, or life.
• Cash flow flexibility. Great for buyers with variable income (bonuses, commissions, freelance).
• Investment property use. Maximize cash flow while holding a property that's appreciating.
• Strategic timing. If you know your income will rise significantly, the lower early payment buys you time.

The cons

• You build no equity during IO period. Your balance stays the same. If the market dips, you could owe more than the house is worth.
• Payment shock. When the IO period ends, your payment jumps 20-30% or more. If you're not prepared, this hurts.
• Higher rates. Interest-only loans typically have rates 0.25-0.75% higher than standard amortizing loans.
• Harder to qualify. Lenders need to see a clear path to handle the higher eventual payment.

When they actually make sense

• Physician loans: Doctors finishing residency who expect their income to triple. The IO period bridges the gap.
• Real estate investors: Buy-and-hold investors who want minimum cash outlay while the property appreciates.
• High-earners with bonus income: People whose base salary covers the IO payment and their bonus handles the rest.
• Short-term ownership: If you plan to sell within the IO period and the property is likely to appreciate.

When to run away

• You're barely affording the IO payment. What happens when it adjusts upward?
• You have no plan for the end of the IO period.
• You're in a flat or declining market.
• You could afford the full payment now — hoarding cash at the cost of building equity.

The takeaway: Interest-only loans are a cash-flow tool, not a free lunch. They work when you have a specific plan for the money you're saving and a clear exit strategy before or when the IO period ends.