Limited Company Buy to Let Mortgages Comparison Calculator
Compare two limited company buy to let mortgage options side by side, estimate monthly payments, first period costs, rental stress test capacity, and identify which deal looks more efficient for your property strategy.
Calculator Inputs
Enter your property details and two mortgage options. This calculator is built for special purpose vehicle and other limited company buy to let comparisons.
Product A
Product B
Results are estimates only and should be checked against lender criteria, SPV setup costs, valuation assumptions, and your accountant or broker advice.
Results
Expert Guide to Using a Limited Company Buy to Let Mortgages Comparison Calculator
A limited company buy to let mortgages comparison calculator helps landlords assess whether one mortgage product is genuinely better than another once interest rate, fees, rental stress testing and ownership structure are considered together. Many investors make the mistake of looking only at headline rates. In practice, the lowest rate is not always the cheapest option, especially if one deal carries a larger arrangement fee, a tougher rental stress test, or a different approach to fees being added to the loan.
For limited company landlords, the comparison process matters even more because the property is usually purchased and financed through a special purpose vehicle, often called an SPV. Lenders can price these cases differently from personal buy to let mortgages, and they may apply specific criteria around SIC codes, directors, personal guarantees, minimum incomes, and rent cover calculations. That means a proper calculator should not only estimate repayments, but also indicate whether expected rental income supports the borrowing level you want.
This page is designed to help you compare two products in a practical way. It estimates the loan from your property value and deposit, then calculates monthly payment, total cost over the period you want to compare, and an estimated maximum loan based on interest coverage ratio and stress rate. While this cannot replace a full lender assessment, it gives a high quality starting point for shortlisting products and speaking to a broker with confidence.
Why limited company buy to let mortgage comparisons are different
Limited company borrowing changes the economics of a buy to let deal. With a personally owned buy to let, individual tax treatment applies. With a company structure, the company receives rental income, pays allowable costs, and may then be subject to corporation tax on profits. Mortgage interest is generally treated differently within a company than it is for an individual landlord. This is one of the main reasons many portfolio investors examine the company route when building a larger property business.
However, mortgage pricing for a company purchase often includes a trade off. A lower interest rate can be paired with a larger fee. Another lender might charge a slightly higher rate but a much smaller fee, making it cheaper over a shorter fixed period. If your strategy is to refinance quickly, sell after a refurbishment, or hold for a long term cash flow play, the best mortgage product can change. That is exactly where a comparison calculator becomes valuable.
Core inputs you should understand before comparing products
- Property value: This helps determine loan to value and the gross borrowing requirement.
- Deposit: Subtracting the deposit from the property value gives the base loan request.
- Mortgage term: Important if you are comparing repayment mortgages, though many buy to let cases are interest only.
- Comparison period: Usually aligned to a fixed rate period such as two years or five years.
- Expected monthly rent: Used for affordability and stress testing.
- ICR: Interest coverage ratio is a lender metric, often 125 percent or higher, used to assess rental affordability.
- Stress rate: A notional rate used by lenders to test whether the rental income supports the loan.
- Fees: Arrangement, valuation, legal and administration costs can materially alter the true cost of a deal.
These inputs matter because buy to let affordability is not assessed in the same way as a mainstream residential mortgage. The lender is often more focused on rent cover and the property as an investment asset. For a limited company borrower, underwriters may also review company structure, shareholders, directors and existing portfolio exposure.
How this calculator evaluates each mortgage product
The calculator compares the products using several lenses rather than a single headline figure:
- Monthly payment: For interest only, this is the annual interest cost divided by 12. For repayment, it uses a standard amortisation formula.
- Total cost over your chosen period: This combines monthly payments over the chosen comparison horizon with fees and recurring annual company costs.
- Net monthly rent before maintenance and voids: This subtracts the estimated mortgage payment from gross rent, which is useful for quick screening.
- Stress tested maximum loan: This uses annual rent, your chosen ICR and each product’s stress rate to estimate the maximum supported borrowing.
If one product is cheaper per month but supports a lower maximum loan, the calculator may reveal an important practical issue: the deal may not fund the purchase as planned. This is why serious investors compare both cost and capacity.
Official figures that matter to limited company landlords
Below are some official UK figures that often influence the overall economics of buying through a company. Tax and legal rules can change, so always check current guidance before committing.
| Official UK company tax figure | Current figure | Why it matters to a buy to let company |
|---|---|---|
| Corporation tax small profits rate | 19% | Can apply to companies with profits up to £50,000, subject to associated company rules and eligibility. |
| Corporation tax main rate | 25% | Can apply where taxable profits exceed £250,000, again subject to the usual rules. |
| Marginal relief band | Between £50,000 and £250,000 | Companies in this range may pay an effective rate between the small profits rate and main rate. |
| Other official property and company figures | Current figure | Relevance when comparing mortgage deals |
|---|---|---|
| Additional dwellings surcharge in England and Northern Ireland | 5% | This can materially increase acquisition cost, which affects deposit planning and total capital required. |
| Companies House confirmation statement cycle | Every 12 months | Reminds investors to include annual company administration in their cost model. |
| Most lenders require personal guarantees from directors | Common market practice | Not a tax figure, but a practical consideration because borrowing is through the company, while risk often still sits personally. |
How to interpret the results like an experienced investor
A good comparison process does not stop at asking, “Which product is cheapest?” Instead, ask a sequence of better questions:
- Does the deal pass the rental stress test for the loan size I need?
- If I choose a lower rate with a bigger fee, how long must I hold the mortgage before it becomes the cheaper option?
- Will adding the fee to the loan improve cash flow enough to justify the extra interest paid?
- How much monthly rent margin remains after mortgage cost, company administration, insurance, repairs and voids?
- Is my strategy income focused, refinance focused, or capital growth focused?
For example, a five year fixed mortgage with a stronger stress rate might allow more borrowing and create a smoother underwriting path, even if the monthly payment is slightly higher. On the other hand, a lower fee product might be ideal when you expect to refinance after a short hold period. The “best” product is the one that aligns with your strategy, not just the one with the most attractive advertisement.
Common mistakes landlords make when comparing limited company buy to let mortgages
- Ignoring fees: Arrangement fees can wipe out the advantage of a lower headline rate.
- Using gross rent alone: Real world profitability must also consider maintenance, insurance, licensing, accountant fees and voids.
- Overlooking the stress test: A product may look cheap but still not support the requested loan.
- Comparing different fixed periods without adjustment: A two year fix and a five year fix should be compared over a rational time frame.
- Not checking company structure: Some lenders prefer straightforward SPVs with buy to let related SIC codes.
- Assuming a company removes personal risk: Directors are frequently asked for personal guarantees.
When a limited company structure can make sense
The limited company route is often considered by portfolio landlords, higher rate taxpayers, and investors who want to retain profits within a business for reinvestment. It can also suit partners who want a different profit extraction method than direct personal ownership allows. Still, this route is not automatically better for every buyer. Mortgage pricing can be higher than personal equivalents, accountancy requirements add cost, and extracting profits personally may trigger further tax considerations. The right answer depends on your expected profits, future portfolio plans, personal tax position and how you intend to use the income.
That is why this calculator should be viewed as a decision support tool, not a substitute for specialist tax advice. It helps you ask the right questions before you move to the next stage.
Useful official resources for further research
- UK Government, corporation tax rates and reliefs
- UK Government, Stamp Duty Land Tax residential property rates
- UK Government, running a limited company and filing duties
Final thoughts
A limited company buy to let mortgages comparison calculator is most powerful when it helps you compare affordability, cost and strategy at the same time. A product with the lowest monthly payment may not be the best after fees. A product with the lowest total period cost may not be suitable if it fails the rental stress test. And a mortgage that fits today could still be wrong for a refinancing or portfolio expansion plan next year.
Use the calculator above to test different deposit levels, rental assumptions and fee structures. Then take your shortlisted options to a specialist broker and accountant. By combining data, lender criteria and tax planning, you will make a stronger and more commercially sound buy to let decision through your limited company.