0% for 12 Months? True 0% vs Deferred Interest, and the Monthly Payment That Avoids Both Traps

• Detail 1: is it true 0% or deferred interest?
• Detail 2: the rate after the promo
• The payment that beats both
• Balance transfers
• One more rule
• Free tools

Card and store offers like “0% for 12 months” can save real money or cost a lot, depending on two details in the small print.

§Detail 1: is it true 0% or deferred interest?

• True 0% intro APR (most bank credit cards and balance transfers): no interest during the promo. When it ends, interest applies only to the balance left from then on.
• Deferred interest (“no interest if paid in full in 12 months”, common on store cards and some medical or furniture financing): interest is calculated from day one in the background. If even $1 remains at the end, all of it can be charged at once.

Example: $1,800 purchase at a 30% deferred rate. Pay $140 a month and $120 remains after 12 months. Instead of interest on $120, you could be charged roughly $300 of back interest on the whole purchase history.

§Detail 2: the rate after the promo

Rates of 30% to 36% after the promo are not unusual on store cards. That is the number that matters if any balance is left.

§The payment that beats both

Monthly payment = balance / promo months, rounded up, plus a small buffer.

$1,800 / 12 = $150. Pay $160 and it is gone a month early. Set it as an autopay amount, not the minimum payment. Minimum payments are often designed to leave a balance at the end of the promo.

§Balance transfers

For a balance transfer, add the transfer fee (often 3% to 5%) to the comparison. A $5,000 transfer with a 4% fee costs $200 up front; it is still a good deal if your current card charges 25%, as long as you clear it within the promo period.

§One more rule

New purchases on a balance-transfer card may not get the 0% rate, and payments may go to the 0% balance first. Keep that card for the transfer only.

§Free tools

• Balance transfer calculator: https://smartbudgetsheets.surge.sh/calculators/balance-transfer-calculator/?utm_source=nostr
• Credit card payoff calculator: https://smartbudgetsheets.surge.sh/calculators/credit-card-payoff-calculator/?utm_source=nostr
• Buy now pay later calculator: https://smartbudgetsheets.surge.sh/calculators/buy-now-pay-later-calculator/?utm_source=nostr
• Debt Payoff Planner, up to 8 debts (Payhip): https://payhip.com/b/PtBLU?utm_source=nostr
• 42 free budget templates, pay what you want ($0 is fine): https://smartbudgetsheet.gumroad.com/l/ngpkrb?utm_source=nostr

General information, not financial advice. Figures are rounded examples.