$2,400 purchase, 12-month deferred interest

  1. Straight-line payoff: $200/month

  2. Safer 11-month target: about $218/month

  3. Promotional balance left at deadline: $100

  4. At 29.99%, retroactive interest could be hundreds of dollars

  5. Minimum payments may not clear the balance in time

Read the sequence from the starting balance through the trigger or exit date.

Follow the decision over time

Read the trigger language

Phrases such as “no interest if paid in full” can indicate deferred interest. “0% APR for 12 months” generally describes a different structure, but the agreement controls.

Build a buffer

Target payoff at least one statement cycle early. This leaves time to correct allocation, returns, delayed credits or an unexpectedly small final payment.

This decision belongs in The Real Cost of Credit Cards. Use Balance Transfer Fees: Calculate the Promotion’s Real Break-Even to check the next assumption, then test the numbers in the Balance Transfer Calculator.

The contract language matters: use the separate comparison to check whether a 0% promotion is truly interest-free.

Other balances interfere

Purchases outside the promotion may change grace periods and payment allocation. Keep the promotional purchase isolated when possible.

Returns are not always payments

A merchant credit may reduce a promotional balance differently or arrive after the deadline. Verify the issuer’s posted balance rather than assuming a pending refund solved it.

Build the decision timeline

Deferred interest has an asymmetric deadline: a small unpaid amount can trigger accrued interest under the contract. Build a payoff buffer before the stated expiry rather than scheduling the last payment on it.

Terms that control the deadline

  • Promotional purchase balance and expiry date.
  • Rate used to accrue deferred interest from purchase.
  • Payment allocation and consequence of any remaining balance.
  • Identify whether interest is waived or deferred.
  • Record the exact expiry date from the statement.
  • Divide the full promotional balance by one fewer cycle.
  • Check allocation when the final two statements arrive.
  • Request written confirmation when the balance reaches zero.

Timing risks that change the cost

  • Paying only the minimum.
  • Using the last day of the promotion as the target.
  • Assuming a return posts before the deadline.
  • Mixing new purchases with the promotional balance.

Test the dates and balances

Balance Transfer Calculator

Test whether the transfer fee buys enough interest savings before the promotion ends.

Questions this decision usually raises

If one dollar remains, is all interest charged?

Many deferred-interest terms can trigger accrued interest when the promotional balance is not paid in full; read the agreement.

Can the issuer move my payment?

Allocation rules can be complex, especially near expiry. Review statements and contact the issuer early.

Is deferred interest always a bad choice?

Not if the price is competitive and payoff is certain, but the downside is asymmetric and deserves a buffer.

Verify the dates, triggers and limits

This page explains a calculation, not a personal recommendation. Contract rules and consumer protections vary by product and jurisdiction. Check the current agreement and official guidance before acting.