Mathematics Standard • Year 11 • Module 3 • Lesson 10
Managing Money, Exam Practice
Practise HSC Mathematics Standard 2-style writing on Managing Money, short answers and one structured extended response that chains tax, budgeting and GST.
Reference, 2023–24 ATO tax brackets (residents), supplied historical table
Rates change between years. Always work from the table supplied with the question, not from a table you have memorised. The current resident rates differ from these, see Earning money lesson 8.
| Taxable income | Tax on this income |
|---|---|
| $0 – $18,200 | Nil |
| $18,201 – $45,000 | Nil + 19c for each $1 over $18,200 |
| $45,001 – $120,000 | $5,092 + 32.5c for each $1 over $45,000 |
| $120,001 – $180,000 | $29,467 + 37c for each $1 over $120,000 |
| $180,001 + | $51,667 + 45c for each $1 over $180,000 |
Medicare levy = 2% of taxable income. GST = 10% (×1.10, ÷1.10, ÷11).
1. Short-answer questions
1.1 A worker has gross fortnightly pay of $2,140. Fortnightly deductions are PAYG tax $352, union $14, super top-up $76. Calculate the fortnightly net pay. 2 marks Band 3
1.2 Aisha earns $72,800 salary and $620 in bank interest. Her allowable deductions total $2,180. Her PAYG withheld was $14,650.
(a) Calculate Aisha's taxable income.
(b) Calculate her total tax liability (income tax + Medicare levy).
(c) State whether she has a refund or debt and the amount. 4 marks Band 3-4
1.3 A 91-day GST-inclusive electricity bill is $487.30. Pre-GST rates: supply $0.98/day; flat usage 27.4c/kWh.
(a) Calculate the pre-GST amount on the printed bill.
(b) Hence determine how many kWh the household used this quarter (to the nearest kWh). 4 marks Band 4
2. Extended response
2.1 Brendan is a software developer. For the 2024–25 financial year he reports the following:
Income: salary $94,400; bank interest $820; rental income from a granny flat $1,640.
Allowable deductions: union/professional fees $560; home-office equipment $1,140; registered DGR donation $300. (Also listed: $480 commute home-to-CBD office, NOT allowable.)
PAYG withheld by employer: $23,800 for the year.
Monthly expenses: rent $2,180; weekly groceries $290; quarterly electricity bill $568 (GST-inclusive); monthly phone $94 (GST-inclusive); annual insurance $1,680 (GST-inclusive).
(a) Calculate Brendan's taxable income (justify excluding the commute).
(b) Calculate his income tax, Medicare levy and total tax liability. State refund or debt.
(c) Convert all monthly expenses to a single monthly figure. Calculate his after-tax monthly cash income (divide annual after-tax income by 12), and find his monthly surplus or deficit. Also state the GST component of the electricity bill. 7 marks Band 5-6
Explicit marking criteria
Part (a), 2 marks
• 1 mark correctly identifies allowable deductions and excludes the $480 commute with a brief reason.
• 1 mark correct taxable income (gross from three sources − allowable deductions).
Part (b), 2 marks
• 1 mark correct income tax + Medicare = total tax liability.
• 1 mark correct refund or debt amount with conclusion sentence.
Part (c), 3 marks
• 1 mark correctly converts weekly/quarterly/annual expenses to monthly and totals them.
• 1 mark correct monthly after-tax cash and monthly surplus/deficit.
• 1 mark correct GST component of electricity using ÷11 on the GST-inclusive amount.
Your response:
How did this worksheet feel?
What I'll revisit before next class:
1.1, Net pay (2 marks)
Sample response.
Total deductions = $352 + $14 + $76 = $442.
Net pay = $2,140 − $442 = $1,698.00 per fortnight.
Marking notes. 1 mark, correctly sums all three deductions. 1 mark, correct net pay with units.
1.2, Aisha's tax (4 marks)
Sample response.
(a) Gross = $72,800 + $620 = $73,420. Taxable income = $73,420 − $2,180 = $71,240.
(b) Income tax = $5,092 + 0.325 × ($71,240 − $45,000) = $5,092 + $8,528 = $13,620. Medicare = $71,240 × 0.02 = $1,424.80. Total liability = $15,044.80.
(c) $14,650 < $15,044.80 → tax debt of $394.80.
Marking notes. (a) 1 mark, correct taxable income (gross with interest, minus deductions). (b) 1 mark, correct income tax. 1 mark, correct Medicare + total liability. (c) 1 mark, correct direction and conclusion sentence.
1.3, Reverse-engineering kWh (4 marks)
Sample response.
(a) Pre-GST = $487.30 ÷ 1.10 = $443.00.
(b) Supply = $0.98 × 91 = $89.18. Usage cost = $443.00 − $89.18 = $353.82. kWh = $353.82 ÷ $0.274 = 1291.31... ≈ 1,291 kWh (to nearest kWh).
Marking notes. (a) 1 mark, uses ÷1.10 (not ÷11). 1 mark, correct pre-GST amount. (b) 1 mark, calculates supply correctly and subtracts to isolate usage cost. 1 mark, correct kWh to nearest unit. Common error: dividing $487.30 by 11 (→ GST component, not pre-GST).
2.1, Brendan's full Managing Money (7 marks): sample Band-6 response with annotations
Sample Band-6 response.
(a) Taxable income.
Gross income = $94,400 + $820 + $1,640 = $96,860.
Allowable deductions = $560 + $1,140 + $300 = $2,000 (the $480 commute is excluded, home-to-regular-workplace travel is not deductible). [1 mark, correct identification + justification of excluded commute.]
∴ Taxable income = $96,860 − $2,000 = $94,860. [1 mark, correct taxable income.]
(b) Tax liability + refund/debt.
$94,860 in $45,001 – $120,000 bracket.
Income tax = $5,092 + 0.325 × ($94,860 − $45,000) = $5,092 + 0.325 × $49,860 = $5,092 + $16,204.50 = $21,296.50.
Medicare = $94,860 × 0.02 = $1,897.20.
∴ Total liability = $21,296.50 + $1,897.20 = $23,193.70. [1 mark, correct total liability.]
PAYG $23,800 > $23,193.70 → ∴ refund of $606.30. [1 mark, correct refund/debt with conclusion sentence.]
(c) Monthly budget and GST.
Monthly expenses: rent $2,180; groceries = $290 × 52 ÷ 12 ≈ $1,256.67; electricity = $568 ÷ 3 ≈ $189.33; phone $94; insurance = $1,680 ÷ 12 = $140.
∴ Total monthly expenses ≈ $2,180 + $1,256.67 + $189.33 + $94 + $140 = $3,860.00. [1 mark, correct conversions and total.]
After-tax annual income = $94,860 − $23,193.70 = $71,666.30. Monthly after-tax cash = $71,666.30 ÷ 12 ≈ $5,972.19.
∴ Monthly surplus = $5,972.19 − $3,860.00 = $2,112.19. [1 mark, correct monthly cash and surplus.]
GST component of electricity bill = $568 ÷ 11 ≈ $51.64. [1 mark, correct GST component using ÷11 on the GST-inclusive amount.]
Conclusion: Brendan has a comfortable monthly surplus of about $2,112, a refund of $606.30 from his tax return, and the GST embedded in his quarterly electricity bill is $51.64.
Total: 7/7.
Band descriptors for marker.
Band 3: Calculates taxable income and income tax but includes the commute as a deduction, OR omits Medicare. ≈ 3 marks.
Band 4: Taxable income, total liability and refund/debt all correct; monthly conversions attempted but at least one expense incorrectly converted. ≈ 4-5 marks.
Band 5: Full numerical solution but bare conclusions in (c) without sentences, OR uses ×0.10 for the GST component on an inclusive price. ≈ 6 marks.
Band 6: Complete: tax, liability, refund correctly chained, all monthly conversions correct, monthly surplus calculated, GST component using ÷11, AND a clear conclusion statement at the end. 7/7.