## Read the Q4 2025 data accurately
UK Finance reported 59,489 new UK buy-to-let loans worth GBP 11.2 billion in Q4 2025. The year-on-year increase was 18.2% by number and 21.3% by value, with growth largely concentrated in remortgage activity.
The same release reported a 4.77% average rate across new buy-to-let loans and a 218% average ICR. Those are portfolio-level market measures, not a product quote or a property-specific borrowing result.
Compare the dated market release with the Bank of England's current [Bank Rate page](https://www.bankofengland.co.uk/monetary-policy/the-interest-rate-bank-rate), but keep both outside the property calculation until a lender supplies the actual product and stress assumptions.
## Rebuild the lender screen
Use the current lender stress rate, ICR, qualifying rent, LTV and fee treatment. The [PRA underwriting statement](https://www.bankofengland.co.uk/prudential-regulation/publication/2016/underwriting-standards-for-buy-to-let-mortgage-contracts-ss) includes ICR and interest-rate affordability stress testing for firms in scope.
The simplified debt calculation is:
**Maximum loan = qualifying annual rent / (stress rate x ICR multiplier)**
For GBP 18,000 annual rent, 5.5% stress and 145% ICR, the [buy-to-let stress and ICR calculator](/tools/buy-to-let-stress-icr-calculator) gives GBP 225,705.33 before LTV.
## Compare with the property ceiling
At GBP 180,000 value and 75% LTV, the property ceiling is GBP 135,000. The lower GBP 135,000 result binds in the controlled example.
Do not substitute the Q4 average rate for the current product stress rate. Preserve the lender criteria and quote date used for the calculation.
Create a remortgage evidence row with current balance, current rate, product end date, early repayment charge, valuation, qualifying rent, proposed product, stress rate, ICR, LTV and fees. Compare the proposed net advance with redemption and transaction costs before labelling cash as released.
Calculate three outputs separately: gross new loan, amount needed to redeem existing debt and fees, and net cash released. A larger gross loan does not imply the same increase in available cash. Keep any retained product fee or redemption charge visible in the bridge between those outputs.
Retain the rejected product cases as well as the selected remortgage case.
## Check the post-remortgage cash flow
Run the [gross and net yield calculator](/tools/gross-net-yield-calculator) with rent, management, maintenance, insurance, void and other operating costs. Keep the lender rent test and net operating result as separate evidence.
The market data explains why remortgage activity changed in that quarter. The property model decides whether the proposed remortgage amount, fees and ongoing cash flow work for the actual deal.