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Aussie Mortgage Calc
by
tianshizhimao-sudo
· GitHub ↗
· v1.1.0
2597
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Install in OpenClaw
/install aussie-mortgage-calc
Description
Australian mortgage calculator — LVR, stamp duty, LMI, repayments, and First Home Buyer concessions by state.
README (SKILL.md)
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
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)
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.
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 | — |
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
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
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.
Usage Guidance
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.
Capability Analysis
Type: OpenClaw Skill
Name: aussie-mortgage-calc
Version: 1.1.0
The skill bundle contains only metadata and a markdown file with informational content about Australian mortgage calculations. There is no executable code, no instructions for the AI agent beyond presenting the information, and no evidence of data exfiltration, malicious execution, persistence, or prompt injection attempts. All URLs provided are for informational purposes (e.g., government revenue offices, the developer's homepage) and are not used in a malicious context.
Capability Assessment
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.
How to Use
- Make sure OpenClaw is installed (local or Docker)
- Run the install command in chat:
/install aussie-mortgage-calc - After installation, invoke the skill by name or use
/aussie-mortgage-calc - Provide required inputs per the skill's parameter spec and get structured output
Version History
v1.1.0
- Major update: SKILL.md expanded to include comprehensive explanations and up-to-date rates for all calculator components.
- Added detailed calculation formulas for LVR, stamp duty (by state), LMI, monthly and interest-only repayments.
- Included First Home Buyer concessions and First Home Owner Grant tables for all states and territories.
- Provided latest (2024-25) stamp duty brackets and eligibility summaries by jurisdiction.
- Added contact links to state revenue offices, plus new disclaimer and lending guidance.
- All figures now explicitly in AUD and reflect current government thresholds.
v1.0.3
- Removed the `metadata` section from the SKILL.md file.
- No other content changes; all feature details and calculations remain the same.
v1.0.2
No user-facing changes in this release.
- No file changes detected from the previous version.
v1.0.1
- Major update: Complete rewrite of documentation for broader audience, with more examples, rates, and explanations.
- Expanded details on LVR, monthly and IO repayments, LMI estimates, and borrowing power rules of thumb.
- Comprehensive 2024–25 stamp duty tables, exemptions, and First Home Buyer benefits for all Australian states and territories.
- Removed CLI usage instructions and command documentation; focuses now on formulae, guides, and practical info.
- Added lender/state revenue office links and a clear disclaimer.
- Two files removed: calculator.js, package.json.
v1.0.0
Australian mortgage calculator - LVR, stamp duty, LMI, repayments for brokers
v0.2.1
- No changes detected in this release.
- Functionality and documentation remain unchanged from the previous version.
v0.2.0
Australian mortgage calculator - LVR, Stamp Duty, LMI, Repayments
v0.1.1
Fix publish - initial release
v0.1.0
Initial release — LVR, Stamp Duty (NSW/VIC/QLD), LMI, Repayment Calculator
Metadata
Frequently Asked Questions
What is Aussie Mortgage Calc?
Australian mortgage calculator — LVR, stamp duty, LMI, repayments, and First Home Buyer concessions by state. It is an AI Agent Skill for Claude Code / OpenClaw, with 2597 downloads so far.
How do I install Aussie Mortgage Calc?
Run "/install aussie-mortgage-calc" in the OpenClaw or Claude Code chat to install it in one step — no extra setup required.
Is Aussie Mortgage Calc free?
Yes, Aussie Mortgage Calc is completely free (open-source). You can download, install and use it at no cost.
Which platforms does Aussie Mortgage Calc support?
Aussie Mortgage Calc is cross-platform and runs anywhere OpenClaw / Claude Code is available (cross-platform).
Who created Aussie Mortgage Calc?
It is built and maintained by tianshizhimao-sudo (@tianshizhimao-sudo); the current version is v1.1.0.
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