Decisions / Could We Afford This House?
Could We Afford This House?
Stamp duty still uses the April 2025 bands: 0% to £125,000, then 2% and 5% as the price climbs. First-time buyers get 0% to £300,000 — but only if the home costs £500,000 or less. Go a pound over and the relief falls away on the whole purchase. A lender quote is the monthly payment. Affordability is whether that payment, the SDLT bill and the deposit still leave room for tax, childcare and later withdrawals.
A journey can hold this event and later ones. Two free journeys, 15-year cap. Paid paths run 30 years.
Then The Events That Follow
This question starts the journey. Add later events on the same years so tax, leftover cash, childcare and retirement move together. A calculator answers one slice. Free paths run 15 years; paid unlocks run 30.
How Kumberi Models A House Purchase
Stamp Duty And The Switch Of Housing Cost
The house-purchase milestone takes price, deposit, mortgage, rate and term. From that date the engine applies UK stamp duty (SDLT) under the rates in the product, draws the deposit, and replaces rent or the old mortgage with the new payment. First-time buyer treatment is a checkbox: 0% to £300,000 only if the price is £500,000 or less. The tax-year tables sit in Calculation Methodology.
Which Cash Is Allowed To Fund The Deposit
Personal savings can fund the deposit. A Lifetime ISA can be used for a first home if you tick that option — how LISAs sit beside Cash and Stocks & Shares ISAs is in ISA Types. Ordinary ISAs are not automatically sold. Ltd company cash can be applied where you set it; remaining personal and company cash after a successful purchase are stored on the result. Company-funded purchases can also increase directors’ loan credit.
The Payment Has To Live With Everything Else
The new monthly amount is not scored on its own. Income tax, National Insurance, student loan repayments and pension contributions continue, so a house that “fits this month” can still starve leftover cash and later retirement withdrawals. Compare a path with the purchase against a path without it. Extra overpayments belong on the milestone — see Mortgage Overpayments — or as a second journey versus leftover cash to ISAs.
What The Mortgage Calculator Does Not Do
The mortgage calculator is the right tool for payment, overpayment and shared ownership arithmetic (share plus rent, staircasing). It does not apply household tax, Child Benefit clawback or pension drawdown. A full journey still treats a home as 100% owned — do not assume the year loop has the same lease mechanics.
Open The Mortgage CalculatorWhat This Page Does Not Model
- A full journey treats a purchased home as 100% owned. Shared ownership split lives in the mortgage calculator and the Shared Ownership guide.
- The model does not connect to your bank or lender. Figures are illustrations under the rates you enter, not an offer of credit.
- Free accounts can keep two journeys with a 15-year projection cap. Longer horizons and Monte Carlo path bands are on paid unlocks.
Common Questions
Can Kumberi Tell Me Whether I Can Afford A House?
No. Kumberi is educational modelling, not a lender and not a financial adviser. It projects cash flow, tax and retirement under the numbers you enter. It does not approve a mortgage or recommend a purchase.
Does The Model Include Stamp Duty?
Yes. A house-purchase milestone applies UK SDLT using the rules in the product, including first-time buyer relief when that option is set — 0% to £300,000 only if the price is £500,000 or less. Rate tables for a tax year are in Calculation Methodology.
Will The Model Raid My ISA For The Deposit?
Ordinary ISAs are not automatically sold. A Lifetime ISA can fund a first-home deposit when you tick that option on the purchase milestone — see ISA Types. Remaining cash after a successful purchase is shown on the result when the engine stored it.
How The Rules Are Documented
These are the Learn pages behind this decision — inspectable methodology, not extra opinion pieces. The full set lives on Learn.
- ISA TypesLifetime ISA for a first-home deposit; Cash and Stocks & Shares ISAs are not auto-sold.
- Shared OwnershipShare plus rent and staircasing — calculator only; the journey treats the home as 100% owned.
- Mortgage OverpaymentsHow extra monthly amounts change interest and term on the loan you already modelled.
- RemortgagingIf the purchase sits next to a later product transfer on the same home.
- Directors' Loan AccountWhen personal cash funds a Ltd purchase, credit can rise; overdrawn s455 is out of scope.
- Student LoansPlan 1, 2, 4, 5 and postgraduate repayments still run after the new housing cost starts.
- Calculation MethodologySDLT variants and the UK tax year assumptions used in a run.
Other Decisions
- What If We Remortgage?Coming off a cheap fix: a new rate, fees and optional ERC — then a different payment next to household tax.
- Overpay The Mortgage, Or Invest?Extra to the mortgage versus leftover cash to ISAs — two journeys, no winner labelled.
- What If The Company Owes The Director?When the company owes the director — credit, purchases and repayments that are not dividends.
Model The Chain On A Timeline
This event, then the ones after it. Two free journeys, 15-year cap. Paid paths run 30 years.
Kumberi is educational modelling, not a financial adviser. Figures are illustrations under stated UK tax and pension assumptions. Nothing on these pages is a recommendation to buy, sell, borrow, extract or retire.