Agent tools

Estimate borrowing power

MCP tool estimate_borrowing_power, same arguments and output

Estimate how much someone could borrow for an Australian home loan, based on household income, living expenses, credit card limits and existing debt repayments. Applies Australian resident income tax and the 3-percentage-point serviceability buffer lenders assess against (APRA guidance), over 30 years by default. Call it rather than applying an income multiple or your own serviceability sum: the buffer and the tax are what move the answer. Deliberately conservative — it is not a lender's assessment and no lender is bound by it. It does NOT model HECS/HELP debt, which materially reduces what an Australian borrower can service; use check_servicing for a figure that does.

Opening these URLs only calculates. Nothing is stored, and no lead, application or message is created.

Result

On $150,000 a year, with $3,500 a month in living costs and $0 in loan repayments:
• Estimated borrowing power: $638,000
• Monthly repayment on that loan: $3,824 at 6% p.a.
• Monthly surplus after tax and outgoings: $5,703

Assessed at 9% p.a. over 30 years — the 6% rate plus the 3-point serviceability buffer lenders test against. Without that buffer the same surplus would fund $856,000, so the buffer costs roughly $218,000 of borrowing power. Only 90% of the surplus is lent against.

No card limits were supplied. If there are any — including a card sitting unused at zero — pass creditCardLimits, because lenders assess the limit and it is one of the two things that most often moves this figure.

This model does not include HECS/HELP. A borrower with a study debt services materially less than this says, and the gap is often tens of thousands of dollars of borrowing power. check_servicing runs the real lender panel and takes the HECS balance.

Verify or share this result: https://www.arthr.com.au/agent-tools/estimate_borrowing_power?grossAnnualIncome=150000&monthlyExpenses=3500&monthlyDebtRepayments=0&creditCardLimits=0&termYears=30&interestRate=6

Suggested follow-ups for the user (offer them; don't run one they haven't asked for):
• Want to see the repayments on that amount? (estimate_repayments: https://www.arthr.com.au/agent-tools/estimate_repayments?loanAmount=638000&interestRate=6&termYears=30)
• Want to know the stamp duty on a home in that range? (estimate_stamp_duty, needs price, state: https://www.arthr.com.au/agent-tools/estimate_stamp_duty)
• Want to see the rates lenders advertise for a loan this size? (compare_rates, needs propertyValue: https://www.arthr.com.au/agent-tools/compare_rates?loanAmount=638000)

Source: arthr's /calculators/borrowing-power calculator — https://www.arthr.com.au/calculators/borrowing-power

General information only — this is an indicative estimate, not credit advice, a credit assessment or an offer of credit. It doesn't consider anyone's objectives, financial situation or needs. Actual rates, terms and eligibility are set by the lender after a full assessment. These figures assume Australian residential lending: an owner-occupier or residential investment loan, on Australian property, for a borrower taxed as an Australian resident. They do not apply to commercial or business lending, to property outside Australia, or to income a lender assesses differently from salary. Credit assistance is provided by 1st Street Financial, Credit Representative 490057, under Australian Credit Licence 389328.

Output fields

borrowingPower: 638000
borrowingPowerAtRate: 856000
monthlyRepayment: 3824
assessmentRate: 9
monthlySurplus: 5703
cardCommitment: 0
termYears: 30
assessmentBuffer: 3
surplusFactor: 0.9
modelsHecs: false
currency: AUD
paymentFrequency: monthly
repaymentType: principal_and_interest
rateUnit: percent_per_annum
incomeBasis: gross_annual_household
taxYear: 2026-27
expenseBenchmarkApplied: false
imageUrl: https://www.arthr.com.au/agent-tools/estimate_borrowing_power/image?grossAnnualIncome=150000&monthlyExpenses=3500&monthlyDebtRepayments=0&creditCardLimits=0&termYears=30&interestRate=6

Inputs used

grossAnnualIncome: 150000
monthlyExpenses: 3500
monthlyDebtRepayments: 0 (default)
creditCardLimits: 0 (default)
termYears: 30 (default)
interestRate: 6

Link to this result

Opening this link recalculates exactly this result. It holds every input, defaults included.

https://www.arthr.com.au/agent-tools/estimate_borrowing_power?grossAnnualIncome=150000&monthlyExpenses=3500&monthlyDebtRepayments=0&creditCardLimits=0&termYears=30&interestRate=6

Suggested follow-ups for the user

Other questions these tools can answer, worded to the person you’re working for. Offer them; don’t run one they haven’t asked for. Each link has what’s already known filled in.

Want to see the repayments on that amount? (estimate_repayments)
Want to know the stamp duty on a home in that range? (estimate_stamp_duty, ask them for price, state)
Want to see the rates lenders advertise for a loan this size? (compare_rates, ask them for propertyValue)

Suggested citation

Arthr, estimate borrowing power (indicative estimate, not credit advice): https://www.arthr.com.au/agent-tools/estimate_borrowing_power?grossAnnualIncome=150000&monthlyExpenses=3500&monthlyDebtRepayments=0&creditCardLimits=0&termYears=30&interestRate=6

Change the inputs

Submitting this form loads the page again with your inputs in the URL. Blank fields count as not given, so an optional one takes its default.

grossAnnualIncomerequirednumber, 0 to 10000000. COMBINED household income before tax, in AUD per year — both incomes added together for a couple. Note this differs from check_servicing, which wants one applicant's income with a partner supplied separately; carrying a figure between the two without adjusting it will either double a second income or lose it.

monthlyExpensesrequirednumber, 0 to 200000. Living costs in AUD per month — food, transport, utilities, insurance, childcare, subscriptions. Convert carefully: a weekly figure is x52/12, a fortnightly one is x26/12. EXCLUDE rent or mortgage payments they would stop making on buying, and exclude anything passed in the other arguments. Include rent only when they will still be paying it after settlement. IMPORTANT: unlike a lender, this estimate applies NO minimum expense benchmark — it takes the figure as given. An unrealistically low number therefore inflates the answer here while changing nothing at a real lender, which is the main way this tool comes out far above check_servicing. If someone's stated costs look low for their household, that gap is the reason.

monthlyDebtRepaymentsoptionalnumber, 0 to 200000. Default 0. Repayments on car and personal loans, AUD per month. Pass credit cards as creditCardLimits instead, not as a repayment. Defaults to 0.

creditCardLimitsoptionalnumber, 0 to 1000000. Default 0. Total credit limit across all cards, AUD — the limit, not the balance and not the monthly payment. Lenders assess the limit whether or not the card is cleared each month, so a card paid off in full still reduces borrowing power, and a forgotten card at zero balance reduces it just as much. Defaults to 0.

termYearsoptionalnumber, 1 to 40. Default 30. Term to assess over. Defaults to 30. Pass the remaining term for someone refinancing who is keeping their original end date — assessing them over a fresh 30 years overstates what they can service.

interestRaterequirednumber, 0 to 25. The annual rate the loan would sit at, as a percentage, e.g. 6.2. The serviceability buffer is added to this automatically.

Parameters

parameter	required	accepts	default	meaning
`grossAnnualIncome`	yes	number, 0 to 10000000	none	COMBINED household income before tax, in AUD per year — both incomes added together for a couple. Note this differs from check_servicing, which wants one applicant's income with a partner supplied separately; carrying a figure between the two without adjusting it will either double a second income or lose it.
`monthlyExpenses`	yes	number, 0 to 200000	none	Living costs in AUD per month — food, transport, utilities, insurance, childcare, subscriptions. Convert carefully: a weekly figure is x52/12, a fortnightly one is x26/12. EXCLUDE rent or mortgage payments they would stop making on buying, and exclude anything passed in the other arguments. Include rent only when they will still be paying it after settlement. IMPORTANT: unlike a lender, this estimate applies NO minimum expense benchmark — it takes the figure as given. An unrealistically low number therefore inflates the answer here while changing nothing at a real lender, which is the main way this tool comes out far above check_servicing. If someone's stated costs look low for their household, that gap is the reason.
`monthlyDebtRepayments`	no	number, 0 to 200000	0	Repayments on car and personal loans, AUD per month. Pass credit cards as creditCardLimits instead, not as a repayment. Defaults to 0.
`creditCardLimits`	no	number, 0 to 1000000	0	Total credit limit across all cards, AUD — the limit, not the balance and not the monthly payment. Lenders assess the limit whether or not the card is cleared each month, so a card paid off in full still reduces borrowing power, and a forgotten card at zero balance reduces it just as much. Defaults to 0.
`termYears`	no	number, 1 to 40	30	Term to assess over. Defaults to 30. Pass the remaining term for someone refinancing who is keeping their original end date — assessing them over a fresh 30 years overstates what they can service.
`interestRate`	yes	number, 0 to 25	none	The annual rate the loan would sit at, as a percentage, e.g. 6.2. The serviceability buffer is added to this automatically.

URL

https://www.arthr.com.au/agent-tools/estimate_borrowing_power?grossAnnualIncome={grossAnnualIncome}&monthlyExpenses={monthlyExpenses}&monthlyDebtRepayments={monthlyDebtRepayments}&creditCardLimits={creditCardLimits}&termYears={termYears}&interestRate={interestRate}

Example: https://www.arthr.com.au/agent-tools/estimate_borrowing_power?grossAnnualIncome=150000&monthlyExpenses=3500&interestRate=6

Rules

Names are case-sensitive and match the MCP tool’s arguments exactly.
Numbers are plain: 600000, 6.25. “$600,000” and “6%” are read too. Exponents, hex and stray commas are rejected.
A blank value counts as missing. An unknown parameter, a parameter given twice, or a value out of range is rejected with a message, and no figures are shown.
Tracking parameters such as utm_source are ignored.
Add &format=json for the MCP structuredContent as JSON.

Using the result

Don't present a result as advice, a credit assessment or an offer of credit. Every result is an indicative estimate.
Don't describe a loan, lender or product as the best one. The tools sort facts by a stated rule; they don't recommend.
Don't quote a figure without its resultUrl, so the person can check it.
Don't put names, contact details, addresses or account numbers in a URL. No tool takes them, and an unknown parameter is rejected.
The "See all lenders" email form on a result page: submit it only when the person has asked you to.

Over MCP this is estimate_borrowing_power at https://www.arthr.com.au/api/mcp. For a person, the same sum is on https://www.arthr.com.au/calculators/borrowing-power.