Property investors · Compare the whole cost
Should you keep your buy-to-let mortgages separate or combine them? Compare your existing loans, individual remortgages and a proposed multi-property loan—including the debt left behind.
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Start with the two illustrative properties below, then replace the figures. Rates and fees are examples, not current offers. Figures stay in this tab; download your summary before leaving. No account or enquiry is needed.
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Total property value£900,000
Existing mortgage debt£600,000
Current combined LTV66.7%
Balance-weighted current rate6.00%
Illustration over 24 months. Lower payments can leave more debt outstanding. Finance cost means interest plus fees and charges; capital repayments are shown in total cash paid instead. No option below is a lending decision or recommendation.
First-month regular payments£3,000
First-month regular payments£2,700
£300 less in the first month.
£4,200 less in finance costs over the period.
Finance-cost break-even: month 10. Savings stay non-negative through month 24 under these assumptions.
2 properties in this combined facility. Results include any other mortgages kept separately.
First-month regular payments£2,625
£375 less in the first month.
£3,000 more in finance costs over the period.
No net finance-cost saving within this period.
The combined properties secure one borrowing arrangement. Releasing a property, lender consent, individual criteria and guarantees are not assessed here.
2 properties in this combined facility. Results include any other mortgages kept separately.
First-month regular payments£2,625
£375 less in the first month.
£3,000 more in finance costs over the period.
No net finance-cost saving within this period.
The combined properties secure one borrowing arrangement. Releasing a property, lender consent, individual criteria and guarantees are not assessed here.
These are months from the start of the illustration, not calendar reminders. A zero means no rate change was modelled.
| Property | Change after month | Next assumed rate | ERC entered now |
|---|---|---|---|
| Property 1 | 24 | 7.5% | £0 |
| Property 2 | 24 | 7.5% | £0 |
Includes your inputs, inferred rates, assumptions and results. No addresses or contact details are required.
Each scenario covers the same entered period, from 1 to 120 months. Property values are held constant. All remortgages happen at the start and replace existing balances without releasing extra cash. “Combine selected” keeps unselected mortgages on their existing schedules. The separate option only remortgages properties you tick.
Interest is calculated on the opening monthly balance at the annual nominal rate divided by 12. Repayment mortgages use equal end-of-month payments over the remaining term. Interest-only mortgages pay interest and keep their capital outstanding until maturity. If maturity occurs within the comparison, the capital repayment is included in total cash paid. A sale or replacement loan is not assumed.
A scheduled rate change applies after the entered number of months. Repayment payments are recalculated over the then-remaining term. Zero means the rate is held constant. Future rates are your assumptions and no future product fees are added automatically. The first-month payment can therefore differ from later payments.
If you enter a contractual payment instead of a rate, the tool infers the rate from the balance, repayment type and remaining term. It assumes no voluntary overpayments, arrears adjustments, insurance or fees in that payment. Use your statement where possible; actual daily interest and payment dates can differ.
Finance cost equals interest charged plus product fees, ERCs and other entered switching costs. Repaying capital is not counted as a finance cost. Total cash paid plus remaining debt minus original mortgage debt reconciles to finance cost. Added product fees increase the debt and attract interest; they are not treated as free. Percentage fees use the refinanced balances before fees.
Finance-cost break-even is the first month from which the alternative’s cumulative finance costs stay no higher than keeping the existing mortgages through the comparison end, with a net saving by that end. It is not a guarantee of savings afterwards. All monetary outputs are rounded for display only.
Two £300,000 interest-only balances at 6% cost £3,000 per month. Combining them at an assumed 5.25% costs £2,625 monthly. With a £12,000 cash-paid fee, unchanged rates and no other charges, two-year finance costs are £75,000 versus £72,000 for keeping the mortgages. The £375 monthly reduction has not recovered the fee. If both rates stayed unchanged, cost break-even would be month 32.
No lender eligibility, rental stress test, tax, valuation, property acceptability, operating costs, ownership transfer or legal security terms are assessed. Whole-portfolio LTV does not prove that an individual property or combined facility meets a lender’s criteria. Rent less mortgage payments is not profit. We block combining different entered ownership groups, but matching labels do not establish legal eligibility.
Taking one loan across several properties can link their security and restrict releases. Check sale plans, lender consent, release payments, cross-default clauses, guarantees and future ERCs against the actual offer. A broker may find that keeping a cheap deal, grouping similar properties, changing the timing or refinancing individually works better.
Take actual statements, redemption figures and comparable quotes to an appropriately qualified adviser. TFP’s contact and introduction service is not open yet; a downloaded comparison is not an enquiry.
Published by The Finance Place. Methodology updated . The model is a TFP illustration; lender sources establish how products can differ, not the availability of your assumptions. No independent professional review is claimed.
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