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B1.2 · Compare credit-card and debit-card costs and incentives

Learn to compare credit-card and debit-card costs and incentives through clear examples and targeted practice.

Ontario Grade 11 Mathematics

Saving, Investing, and Borrowing

MEL3E study topic B1.2

At a checkout, a debit card and a credit card can both pay for the same lunch. But their costs may differ. A debit purchase usually takes money from a bank account. A credit purchase adds to a balance that must be repaid. The account plan, card agreement, and the way you use the card can affect the total cost. This lesson shows how to compare those costs and any incentives, such as rewards. The goal is not to label one card as always better. It is to use the available information to make a fair comparison.

What you will learn

Identify common costs and incentives shown in debit- and credit-card information.
Use a calculator or spreadsheet to compare costs for the same purchases and time period.
Choose a card based on the situation, while checking the conditions behind fees, interest, and rewards.

1. Know what you are comparing

A debit card lets you use money held in a bank account. Depending on the account, the bank may charge a monthly fee, a fee for some transactions, or a fee if the account balance goes below zero. A purchase may also count toward a limit on included transactions. Check the account details instead of assuming every debit purchase is free.

A credit card lets you borrow up to a set limit. A purchase adds to the amount you owe. A card may have an annual fee, transaction fees, or interest if you do not pay the required amount by the due date. Interest is the amount charged for borrowing. The amount can depend on the card terms and what you owe. For a fair comparison, use the interest charge actually shown or a clearly stated example amount.

An incentive is a benefit meant to encourage a choice or activity. Credit-card incentives can include rewards or cash back on eligible purchases. A bank account may also offer benefits, such as a lower fee when you meet certain conditions. A reward is not the same as cash saved automatically: check what purchases qualify, whether there is a limit, and how the reward can be used.

Compare the same purchases over the same period. Include fees that apply to that situation, and subtract a reward only if the purchases qualify. Read conditions carefully. A low advertised fee may depend on keeping a minimum balance or meeting another requirement.

Debit uses money in an account; credit creates an amount to repay.
Possible costs include account fees, card fees, and credit-card interest.
Possible incentives include eligible rewards or account benefits.
Compare like with like: same purchases, time period, and conditions.

2. Organize the information before calculating

Start with the card or account information. Look for the fee amount, how often it is charged, what purchases earn rewards, and what must happen for a fee or reward to apply. If a detail is missing, do not guess. Ask the bank or use a clearly stated assumption.

Next, choose a time period, such as one month or one year. Convert each cost to that period using repeated arithmetic. For example, if a fee is charged each month, add that monthly fee for each month in the year. A calculator helps prevent arithmetic errors. A spreadsheet can keep the comparison organized.

A simple spreadsheet might have columns for the card, fees, interest, rewards, and total cost. Enter costs as positive amounts and rewards as amounts to subtract. Keep notes about assumptions, such as paying the credit balance in full or making a certain number of transactions. This helps explain why your comparison may change if your habits change.

Do not compare a credit card’s reward with a debit account’s fee while leaving out credit interest that applies. Also avoid counting a reward for purchases that do not qualify. First list all applicable costs and benefits, then calculate the result.

Use one time period for both options.
Include only costs and incentives that apply to the stated situation.
Use a calculator or spreadsheet to add repeated fees and organize results.
State assumptions so another person can follow the comparison.

3. Decide what the comparison means

After adding costs and subtracting eligible rewards, compare the totals. The option with the lower total cost is less costly for the stated situation. If one option has a higher total, the difference tells you how much more it costs over that period.

A credit card may look less costly when a reward is larger than its fees, especially if the balance is paid in full and no interest is charged. But carrying a balance can add interest and change the result. A debit account may have a monthly fee but no credit-card interest for purchases. Its costs still depend on the account terms and how it is used.

Cost is not the only detail a person may consider. A person might value a particular reward or prefer to avoid borrowing. Those are personal priorities, not proof that a card is cheaper. For this expectation, use the fees and incentives to explain the cost comparison, and describe the conditions that could change it.

Before deciding, check the card agreement and account information for current terms. Fees and offers can change. A careful comparison is about the stated facts, not a promise that one kind of card is always the best choice.

A lower total means lower cost for the situation and time period compared.
Interest and reward conditions can change a credit-card comparison.
Explain assumptions and personal priorities separately from the cost result.

4. A practical comparison routine

Use this routine when comparing sample offers or your own card information. First, choose the same time period for both options. Second, list every fee and interest amount that applies. Third, list incentives and confirm their conditions. Fourth, use repeated addition or a calculator to total each side. Finally, state which costs less and name a condition that could change the result.

When information is shown in a statement, use the actual amounts where possible. When information is shown as an offer, read the small print and make your assumptions clear. If a credit offer gives a reward percentage but no information about eligible purchases, you cannot assume every purchase earns that reward. Find the missing detail before making a firm comparison.

Choose a period, list applicable costs, check incentives, total, and explain.
Use statement amounts or clearly stated assumptions.
Missing information is a reason to investigate, not to invent a number.

What to check before comparing

Item	Debit account or card	Credit card
Possible costs	Monthly account fee; transaction fees; possible overdraft fee	Annual or transaction fees; interest when charged
Possible incentives	Account benefits, if conditions are met	Rewards or cash back on eligible purchases
Useful information	Fee schedule and transaction limits	Card agreement, statement, reward rules, and due date

Worked example

Example 1: A yearly fee and a reward

A debit account charges CAD 4 each month. A credit card has no annual fee and gives 1% back on eligible purchases. A person expects to make CAD 240 of eligible purchases each month and pays the credit balance in full, so the example has no interest charge. Compare the card costs over one year. Ignore any account benefits not listed.

Find the debit account fee
The fee is charged each month. Add the same amount for all 12 months to get the yearly cost.
$12 × \text{CAD }4=\text{CAD }48$
Find yearly eligible purchases
The person makes the same amount of eligible purchases each month. Add the monthly amount for 12 months.
$12 × \text{CAD }240=\text{CAD }2{,}880$
Find the credit reward
One percent means one hundredth of the eligible purchase total. The reward is CAD 28.80 for the year.
$\text{CAD }2{,}880 × 0.01=\text{CAD }28.80$
Compare the yearly costs
The debit cost is CAD 48. The credit card has no annual fee or interest in this example, so subtract its reward from its listed costs. The credit result is a net benefit of CAD 28.80. The difference between the debit cost and that result is CAD 76.80.
$\text{CAD }48-(-\text{CAD }28.80)=\text{CAD }76.80$

Answer: Under these assumptions, the credit card has a lower net cost by CAD 76.80 over the year.

Check: The credit-card result depends on all purchases being eligible and the balance being paid in full. If either condition changes, recalculate.

Worked example

Example 2: Interest changes the result

For one month, a debit account charges no monthly fee but charges CAD 0.50 for each of 8 debit transactions. A credit card has no annual fee. Its statement shows CAD 9 of interest for the month, and the cardholder earns CAD 3 in eligible rewards. Compare the costs for this month, using only these listed amounts.

Find debit transaction fees
Multiply the fee for one transaction by the number of transactions to find the total debit fees.
$8 × \text{CAD }0.50=\text{CAD }4$
Find the credit-card net cost
The statement lists CAD 9 of interest. Subtract the CAD 3 reward because it applies to eligible purchases.
$\text{CAD }9-\text{CAD }3=\text{CAD }6$
Compare the totals
The debit cost is CAD 4 and the credit-card net cost is CAD 6. The credit option costs CAD 2 more for this month.
$\text{CAD }6-\text{CAD }4=\text{CAD }2$

Answer: The debit option costs less by CAD 2 for this month, based on the listed amounts.

Check: The reward reduces the credit cost, but it does not fully offset the interest charge. A different number of debit transactions or a different interest charge could change the comparison.

Common mistakes and how to avoid them

Comparing a monthly debit fee with a yearly credit-card fee.

Correction: Put both amounts in the same time period before comparing.

Subtracting rewards for purchases that do not qualify.

Correction: Check the reward rules and count only eligible purchases.

Ignoring interest when a credit balance is carried.

Correction: Include the interest amount that applies to the situation or statement.

Saying one card type is always cheaper.

Correction: Give a conclusion for the stated facts and identify conditions that could change it.

Lesson summary

Debit purchases use account money; credit purchases add to an amount owed.
Fees, interest, and rewards depend on card terms and use.
Use the same time period and include only amounts that apply.
A calculator or spreadsheet can organize repeated fees and incentives.
State assumptions and explain why the result could change.

Check your understanding

Question 1

A debit account fee is CAD 3 per month. What is the fee for 6 months?

CAD 9
CAD 18
CAD 36
CAD 3

Show answer and explanation

CAD 18

Add the monthly fee six times: 6 multiplied by CAD 3 is CAD 18.

Question 2

A credit card charges CAD 7 interest for a month. The cardholder earns CAD 2 in eligible rewards. What is the net cost from these amounts?

CAD 9
CAD 5
CAD 2
CAD 7

Show answer and explanation

CAD 5

Subtract the eligible reward from the interest charge: CAD 7 minus CAD 2 is CAD 5.

Question 3

A card offer lists rewards but does not say which purchases qualify. What is the best next step?

Assume all purchases qualify
Ignore all card costs
Check the reward conditions before calculating
Count the reward twice

Show answer and explanation

Check the reward conditions before calculating

You need the eligibility rules to know which purchases earn rewards. Do not invent missing information.

Key terms

Debit card: A card that uses money held in a bank account for purchases.
Credit card: A card that lets the user borrow for purchases and repay the amount owed.
Interest: A charge for borrowing money, when it applies under the card terms.
Incentive: A benefit offered to encourage a choice or activity.
Eligible purchase: A purchase that meets the rules for earning a reward.
Net cost: Costs after subtracting applicable benefits, such as eligible rewards.

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View the complete Ontario Grade 11 Mathematics learning path

About this lesson

Published by DoAssignment. This AI-assisted lesson follows Ontario Grade 11 Mathematics (MEL3E), expectation B1.2. It is a study resource, not an official curriculum publication.

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