Limited company buy to let mortgage accountant letter interest only products are becoming increasingly popular among UK landlords in 2025. These specialist buy-to-let lending solutions are designed for investors purchasing or remortgaging rental properties through a limited company structure, using an interest-only repayment model. Lenders often require an accountant’s letter to confirm the financial viability of the company and the applicant’s income position.
This type of landlord mortgage offers several advantages, including potential tax efficiencies, especially in light of Section 24 tax changes, and more favourable affordability calculations based on rental income rather than personal income. With rising BTL mortgage rates and tighter regulations, many portfolio landlords and first-time investors are turning to limited company structures to optimise investment property finance. In today’s market, understanding the criteria, deposit requirements, and lender expectations is essential to secure the right deal.
Quick Facts
– Interest rates: 4.5% to 6.5% (2025 average)
– Minimum deposit: 25% (some lenders may require more for HMOs or multi-units)
– Rental coverage: 125% to 145% of mortgage interest at a stress-tested rate
– Maximum loan-to-value (LTV): 75%
– Arrangement fees: Typically 1% to 2% of loan amount
– Application timeline: 4 to 8 weeks from submission to completion
Limited company buy-to-let mortgages typically feature higher interest rates than residential products but offer greater flexibility for tax planning. Lenders assess affordability based on rental income, requiring a rental stress test, and often request a letter from a qualified accountant to confirm the company’s trading status and financial position.
How This Mortgage Works
A limited company buy to let mortgage accountant letter interest only is a mortgage product specifically designed for landlords purchasing or refinancing rental properties through a special purpose vehicle (SPV) or trading limited company. The “interest only” element means borrowers pay only the interest each month, keeping monthly repayments lower, with the capital repaid at the end of the term or via sale or remortgage.
Lenders require an accountant’s letter to verify the company’s financial standing, confirm tax compliance, and sometimes to clarify the applicant’s income or director’s loan status. This is especially important when the company is newly formed or has limited trading history.
Mortgage types include fixed-rate (commonly 2 to 5 years), variable, and tracker options. Fixed rates provide repayment certainty, while tracker products can be more flexible but are subject to Bank of England base rate fluctuations.
This mortgage suits portfolio landlords, investors with multiple properties, and those seeking to mitigate tax exposure. It also appeals to first-time landlords who plan to scale their property business. Lenders are increasingly open to limited company applications, although criteria can vary significantly.
Compared to residential mortgages, these products are assessed on rental income rather than personal affordability, and borrowers are not subject to the same consumer protection rules under the FCA’s Mortgage Conduct of Business (MCOB) regulations.
Eligibility and Criteria
To qualify for a limited company buy to let mortgage accountant letter interest only, applicants must meet a range of lender criteria, which vary depending on the lender, property type, and applicant profile.
Income Requirements:
While personal income is not always a key factor, some lenders prefer directors to have a minimum income (e.g., £25,000+ per annum) to cover potential void periods. Others focus solely on rental income, particularly for SPVs.
Rental Coverage and Stress Testing:
Lenders apply a rental stress test to ensure the property generates sufficient income to cover the mortgage. Typically, this is 125% to 145% of the interest payment, calculated at a stressed rate (e.g., 5.5% or higher). For limited companies, the stress rate may be lower than for personal name applications, due to different tax treatment.
Property Type:
Standard buy-to-let properties (single-family homes or flats) are widely accepted. However, HMOs, multi-unit blocks, and non-standard constructions may require specialist lenders. New builds and flats above commercial premises can also face restrictions.
Credit Score and History:
A clean credit history is preferred, although some lenders will consider minor adverse credit. A good credit score improves access to better rates and terms.
Age and Employment:
Most lenders set minimum and maximum age limits (typically 21 to 85 at term end). Employment type matters less, but self-employed applicants may need to show trading history via accounts or accountant confirmation.
Portfolio Landlords:
Landlords with four or more mortgaged properties are classed as portfolio landlords and must provide detailed property schedules, business plans, and cash flow forecasts. Lenders assess overall portfolio performance and exposure.
Limited Company Structure:
SPVs with SIC codes related to property letting (e.g., 68209) are preferred. Trading companies may be accepted but face more scrutiny. The company must be registered in the UK, and all directors/shareholders are usually underwritten.
Compliance:
Applicants must comply with right-to-rent checks, local licensing schemes (e.g., selective licensing), and energy efficiency regulations (minimum EPC rating of E, rising to C in future proposals).
Costs and Affordability
Limited company buy to let mortgages come with several costs beyond the interest rate. Arrangement fees typically range from 1% to 2% of the loan amount, and may be added to the loan. Valuation fees vary based on property type and value, while legal fees are usually higher for limited company applications due to added complexity.
Interest rates for limited company BTLs are generally higher than personal name equivalents, reflecting perceived risk. Fixed rates offer stability, while variable or tracker rates may be lower initially but carry rate rise risk.
Rental income is the primary basis for affordability. Lenders assess the property’s projected rent against the mortgage payment using a stress test. An accountant’s letter may be required to confirm the company’s trading status and director’s income or loan contributions.
Section 24 tax changes no longer allow individual landlords to deduct full mortgage interest from rental income. Limited companies are exempt, allowing mortgage interest to be treated as a business expense—making interest-only loans more tax-efficient.
Landlords must also budget for insurance (buildings and landlord cover), maintenance, and potential void periods. Lenders stress test affordability at higher interest rates to ensure sustainability.
The Application Process
Applying for a limited company buy to let mortgage accountant letter interest only involves several key steps:
1. Research: Identify suitable lenders or consult a specialist mortgage broker with experience in limited company BTLs.
2. Pre-Assessment: Confirm eligibility, company structure, and rental income projections.
3. Documentation: Prepare company accounts, accountant’s letter, proof of ID, property details, and business bank statements.
4. Decision in Principle: Obtain a DIP from the lender to confirm initial approval.
5. Valuation: The lender will instruct a property valuation to assess market value and rental potential.
6. Underwriting: The lender reviews all documents, including the accountant’s letter, company structure, and rental figures.
7. Legal Work: Solicitors handle conveyancing, company checks, and director guarantees.
8. Completion: Once all checks are complete, funds are released, and the mortgage completes.
Applications typically take 4 to 8 weeks. Working with a mortgage broker can speed up the process, help match you with suitable lenders, and reduce the risk of rejection.
Common reasons for decline include insufficient rental coverage, non-compliant company structure, adverse credit, or missing documentation. Ensuring your accountant provides a comprehensive letter and your business is properly set up is crucial.
Benefits, Risks and Alternatives
Limited company buy to let mortgage accountant letter interest only products offer several benefits:
– Tax efficiency: Mortgage interest is fully deductible for limited companies.
– Lower monthly payments: Interest-only structure reduces cash flow pressure.
– Professional structure: Suitable for scaling portfolios and succession planning.
– Access to specialist lenders: More options for complex cases.
However, there are risks:
– Interest-only loans require a repayment strategy.
– Void periods can impact affordability.
– Regulatory changes (e.g., EPC rules, licensing) may affect profitability.
– Higher interest rates and fees compared to personal BTLs.
Alternative finance options include bridging loans (for short-term purchases or refurbishments), commercial mortgages (for mixed-use or multi-unit blocks), and development finance (for new builds or conversions). When remortgaging, consider whether a product transfer with your current lender is more cost-effective than a full remortgage.
Frequently Asked Questions
What deposit do I need for a limited company buy to let mortgage accountant letter interest only?
Most lenders require a minimum deposit of 25% for limited company buy-to-let mortgages. However, for higher-risk properties such as HMOs or flats above shops, lenders may ask for 30% or more. A larger deposit can unlock better interest rates and improve affordability assessments. Always check the specific lender’s LTV criteria.
Can I get limited company buy to let mortgage accountant letter interest only through a limited company?
Yes, many UK lenders offer buy-to-let mortgages specifically for limited companies. The company must usually be an SPV with a relevant SIC code (e.g., 68209). Lenders will assess the directors and shareholders, and often require an accountant’s letter to confirm trading status and financial health. This structure can offer tax advantages under current legislation.
What rental coverage do lenders require?
Rental coverage is typically between 125% and 145% of the monthly mortgage interest, calculated at a stress-tested rate (often 5.5% or higher). For limited company applications, some lenders apply a lower stress rate (e.g., 4.5%) due to the different tax treatment. The exact coverage ratio depends on the product, borrower profile, and property type.
How does Section 24 tax affect buy-to-let mortgages?
Section 24 of the Finance Act 2015 restricts individual landlords from deducting mortgage interest from rental income, reducing tax relief to a basic rate credit. This has made limited company structures more attractive, as companies can still deduct full interest as a business expense. This change has driven