Aussie Mortgage Calc

Australian mortgage calculator — LVR, stamp duty, LMI, repayments, and First Home Buyer concessions by state.

Security Scan

This instruction-only skill is internally consistent with an Australian mortgage calculator: it contains formulas and state stamp-duty/FHOG/LMI guidance and requests no credentials, binaries, or installs.

Purpose & Capability

The name/description (Australian mortgage calculations) match the SKILL.md content (LVR, repayments, stamp duty by state, LMI, FHOG, borrowing heuristics). There are no unrelated required env vars, binaries, or config paths.

Instruction Scope

SKILL.md is purely descriptive: formulas, tables, examples, and links to official state revenue sites. It does not instruct the agent to read files, call external endpoints, or exfiltrate data. Note: tax/stamp-duty numbers are labeled 2024–25 and could become out of date — accuracy is a non-security concern but relevant for correctness.

Install Mechanism

No install spec and no code files are present — lowest-risk posture (nothing is written to disk or installed).

Credentials

No environment variables, credentials, or config paths are requested. The skill does not require access to secrets or external services.

Persistence & Privilege

always is false and there are no install actions that would persist state or modify other skills. The skill can be invoked by the agent (default), which is normal and acceptable given its limited scope.

Scan Findings in Context

[no-findings] expected: Regex scanner had no code to analyze (instruction-only SKILL.md). Absence of findings is expected for an instruction-only skill.

Assessment

This skill appears coherent and low-risk: it only provides formulas and state-specific rates and does not request credentials or install code. Before relying on results, verify key rates/thresholds against the official state revenue sites linked in the SKILL.md (stamp duty and FHOG change over time). Avoid pasting highly sensitive personal data (full IDs, bank account numbers) into any skill input. If you want automated quoting or lender-specific calculations, prefer a vetted official tool or service that requires explicit, minimal credentials rather than adding networked skills.

Australian Mortgage Calculator

Comprehensive mortgage calculations for Australian property buyers. All amounts in AUD.

Quick Calculations

LVR (Loan to Value Ratio)

LVR = (Loan Amount / Property Value) × 100

Example:
- Property: $800,000
- Loan: $640,000
- LVR: 80%

Monthly Repayment (P&I)

M = P × [r(1+r)^n] / [(1+r)^n – 1]

Where:
- P = Principal (loan amount)
- r = Monthly interest rate (annual rate / 12)
- n = Total months (loan term × 12)

Example: $500,000 loan at 6.5% over 30 years
- Monthly rate: 0.065/12 = 0.00542
- Months: 360
- Monthly repayment: $3,160

Interest Only Repayment

Monthly IO = Principal × (Annual Rate / 12)

Example: $500,000 at 6.5%
- Monthly IO: $2,708

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Stamp Duty by State (2024-25)

NSW (New South Wales)

Property Value	Duty Rate
$0 – $16,000	1.25%
$16,001 – $35,000	$200 + 1.50% of excess
$35,001 – $93,000	$485 + 1.75% of excess
$93,001 – $351,000	$1,500 + 3.50% of excess
$351,001 – $1,168,000	$10,530 + 4.50% of excess
Over $1,168,000	$47,295 + 5.50% of excess

First Home Buyer: Full exemption up to $800,000; concession $800,001-$1,000,000

VIC (Victoria)

Property Value	Duty Rate
$0 – $25,000	1.4%
$25,001 – $130,000	$350 + 2.4% of excess
$130,001 – $960,000	$2,870 + 6.0% of excess
Over $960,000	5.5% flat

First Home Buyer: Full exemption up to $600,000; concession $600,001-$750,000

QLD (Queensland)

Property Value	Duty Rate
$0 – $350,000	1.0% (min $0)
$350,001 – $540,000	$3,500 + 3.5% of excess
$540,001 – $1,000,000	$10,150 + 4.5% of excess
Over $1,000,000	$30,850 + 5.75% of excess

First Home Buyer: Full exemption up to $700,000 (for new homes); concession for established

WA (Western Australia)

Property Value	Duty Rate
$0 – $120,000	1.9%
$120,001 – $150,000	$2,280 + 2.85% of excess
$150,001 – $360,000	$3,135 + 3.80% of excess
$360,001 – $725,000	$11,115 + 4.75% of excess
Over $725,000	$28,453 + 5.15% of excess

First Home Buyer: Full exemption up to $430,000; concession $430,001-$530,000

SA (South Australia)

Property Value	Duty Rate
$0 – $12,000	1.0%
$12,001 – $30,000	$120 + 2.0% of excess
$30,001 – $50,000	$480 + 3.0% of excess
$50,001 – $100,000	$1,080 + 3.5% of excess
$100,001 – $200,000	$2,830 + 4.0% of excess
$200,001 – $250,000	$6,830 + 4.25% of excess
$250,001 – $300,000	$8,955 + 4.75% of excess
$300,001 – $500,000	$11,330 + 5.0% of excess
Over $500,000	$21,330 + 5.5% of excess

First Home Buyer: No stamp duty for properties up to $650,000 (eligible buyers)

TAS (Tasmania)

Property Value	Duty Rate
$0 – $3,000	$50
$3,001 – $25,000	$50 + 1.75% of excess
$25,001 – $75,000	$435 + 2.25% of excess
$75,001 – $200,000	$1,560 + 3.50% of excess
$200,001 – $375,000	$5,935 + 4.00% of excess
$375,001 – $725,000	$12,935 + 4.25% of excess
Over $725,000	$27,810 + 4.50% of excess

First Home Buyer: 50% duty discount for properties up to $600,000

NT (Northern Territory)

Property Value	Duty Rate
$0 – $525,000	V = 0.06571441 × V^2 ÷ 1000
Over $525,000	5.45% flat minus $4,823.45

First Home Buyer: Up to $18,601 discount for properties under $650,000

ACT (Australian Capital Territory)

Property Value	Duty Rate
$0 – $260,000	$0.60 per $100 or part
$260,001 – $300,000	$1,560 + $2.20 per $100
$300,001 – $500,000	$2,440 + $3.40 per $100
$500,001 – $750,000	$9,240 + $4.32 per $100
$750,001 – $1,000,000	$20,040 + $5.90 per $100
$1,000,001 – $1,455,000	$34,790 + $6.40 per $100
Over $1,455,000	$63,910 + $4.54 per $100

First Home Buyer: Full exemption up to $1,000,000 (income-tested)

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LMI (Lenders Mortgage Insurance)

LMI is required when LVR > 80%. Estimated rates:

LVR	LMI as % of Loan
80.01% – 85%	0.5% – 1.0%
85.01% – 90%	1.5% – 2.5%
90.01% – 95%	3.0% – 4.5%

Example: $600,000 loan at 90% LVR

• LMI estimate: ~$12,000 – $15,000 (can be added to loan)

Note: Actual LMI varies by lender, LVR tier, loan amount, and borrower profile. Use lender calculators for exact quotes.

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First Home Owner Grant (FHOG)

State	Grant Amount	Property Cap
NSW	$10,000	$600,000 (new homes only)
VIC	$10,000	$750,000 (regional: higher)
QLD	$30,000	$750,000 (new homes only)
WA	$10,000	$750,000 (new homes)
SA	$15,000	$650,000 (new homes only)
TAS	$30,000	$600,000 (new homes only)
NT	$10,000	No cap (new homes)
ACT	Abolished	—

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Borrowing Power (Quick Estimate)

Basic rule of thumb:

Max Borrowing ≈ (Annual Income × 6) – Existing Debts

More conservative:
Max Borrowing ≈ (Annual Income × 5) – Existing Debts

Factors affecting actual borrowing power:

• Income type (PAYG vs self-employed)
• Existing debts (credit cards, HECS, car loans)
• Living expenses (HEM benchmark)
• Interest rate buffer (usually +3%)
• Dependents

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Key Contacts

• Revenue NSW: revenue.nsw.gov.au
• State Revenue Victoria: sro.vic.gov.au
• Queensland Treasury: qld.gov.au/housing
• WA RevenueWA: wa.gov.au/revenuelicensing
• RevenueSA: revenuesa.sa.gov.au
• Tasmania State Revenue: treasury.tas.gov.au
• NT Treasury: treasury.nt.gov.au
• ACT Revenue: revenue.act.gov.au

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Disclaimer

This skill provides estimates for educational purposes only. Stamp duty rates, concessions, and grants change periodically. Always verify with official state revenue offices and consult a qualified mortgage broker or financial advisor before making property decisions.

Built by Oney & Co — Helping Australians navigate lending with clarity.