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More about Complex Buy-to-Let Mortgages

There are various reasons why a case may be considered complex, this could be due to the client; perhaps having adverse credit, issues with income, or limited experience. Another factor could be the property; it's construction type or location. 

Lots of our lenders are challenger banks and tier two lenders who we can always refer complex applications to, often agreeing exceptions outside their policy including requirement for  more lenient stress testing and varied application type (Ltd Co, Off-Shore)

Individuals and limited companies can apply.

Depending on lenders, this can extend to borrowers who are first-time landlords, self-employed, have impaired credit and expat or foreign nationals.

Landlords can access complex Buy-to-Let mortgages through intermediaries who can help them simplify the process.

With over 20 years of experience in specialist finance, Aria Finance are one of the leading specialist finance distributors who can provide fast access to a vast panel of lenders. As a team we pride ourselves on speed of service, rapid turnaround times and first class customer experience. Due to our experience and access to the lending market we have more flexible criteria on things such as income, adverse credit, property construction type, minimal experience, portfolio landlord, more lenient stress testing, application type (Ltd Co, Off-Shore).

Different lenders will have their own eligibility checks

What eligibility checks will there be?

They will typically check the borrowers:


  • Ability to pay the deposit and source of funds
  • Income (2 year’s SA302) credit and assets
  • Last 3 months’ personal and /or business bank statements as appropriate to verify rental income
  • Proof of ID (certified copy of passport or driving licence)
  • Proof of residency (utility bill or bank statement)
  • Lease copy (AST or commercial lease)

What is the difference between residential, semi-commercial and commercial buy-to-let?


Relates to buy-to-let properties where tenants occupy them as their home, with no commercial element, which can include houses, flats, HMO’s and Multi-Unit Freeholds Blocks. BTL residential rates are lower and cheaper than semi-commercial and commercial properties. 


Relates to mixed use properties that consists of at least one residential unit and at least one commercial unit, all on the same title, typically freehold. The residential unit must be self-contained with its own access and entrance. Semi-Commercial rates are lower and cheaper than fully commercial properties.


Relates to fully commercial units only with no separate self-contained residential unit. Commercial mortgages are available on semi-commercial properties where there is just one lease and tenant who occupies the whole property themselves.

What types of property are classified as ‘residential buy-to-let’?


 HMO, MUFB, Holiday Lets & Standard BTL

What sort of properties can be purchase or re-financed with complex Buy-to-Let mortgages?

Although this will vary between lenders, here are a range of properties that can often be financed with complex Buy-to-Let mortgages:

  • Serviced accommodation and student residences
  • Houses in multiple occupation (HMO)
  • Freehold properties split into several flats
  • Flats near to or above commercial premises such as shops, including fast food and takeaways
  • Ex local authority flats
  • Holiday let
  • Airbnb

Frequently Asked Questions

You can be 1st time buyer, 1st time landlord up to 75% LTV. No minimum income, no stress testing, must be able to prove source of wealth and deposit funds for purchase applications, must pass basic due diligence tests on KYC. The client is not required to visit the UK at any point as long as their solicitors are UK compliant with the lenders solicitors.

We can generally lend up to 65% LTV on the vacant possession value. Can consider up to 75% LTV on referral subject to a strong valuation report, positive comments, excellent demand, etc.

Must have a tenant in place or lined up on completion. Can accept licenses as well as long term commercial leases. Some lenders require proof of continuous use during the lockdown period and rental payments from tenant. Can be 1st time commercial landlord, no minimum personal income or age.

We also offer owner occupier and trading business mortgages and require the last 2 years full trading accounts. Although, this is not always necessary as we can also consider year 1 projections in some instances.

Rates typically begin from 4.49%. This will vary between lenders provisional to the loan amount and the length of term.

The overall amount that can be borrowed is entirely based on the achievable rental income. In some instances, we can also top slice and use a clients personal income to support the application with the view of lending more where required.

All lenders typically use a ‘stress test’ to assess the suitability of the borrower for a BTL mortgage.The stress test considers the rental income and the ability to pay the interest on the mortgage, or the Interest Cover Ratio (ICR). In some instances some of our lender do not stress test and can lend up to 100% coverage.

As an example, a mortgage of £400,000 with a 5.5% ICR applied will result in monthly interest payments on the BTL mortgage of £1833.33 (£400,000 x 5.5% = £22000 / 12 months = £1,833.33). With the rental income of 125%, the actual monthly cost would be £2,291.66 – and this, is the lender’s expected rental value PCM.

For higher tax rate payers, the stress testing increases from 125% to 140%-145%. The stress test applies to the total loan amount, not the property price.

With the complex BTL market, there is flexibility available in the ICR required. Standard calculations start at 125% at 5% for lower rate taxpayers and 140% at 5% for higher rate taxpayers. This means clients can access greater loan amounts than through the traditional high street lenders as standard. As with traditional lenders, borrowers can access lower stress rates when applying for longer fixed rate products over a 5 year or longer term. In the specialist market this starts from 4.49%% giving much greater lending capacity.

Yes, we have no limits.

No, we have no limits.


Typical repayment terms are 5 – 30 years.

Yes, as long as you can prove an application has been submitted and lodged with an undertaking to forward the HMO license post completion, typically up to 3 months after completion

Some lenders may consider up to 80% loan-to-value (LTV) for a residential complex BTL and 75% LTV for a commercial complex BTL mortgage, however 75% LTV is more typical, so you should be prepared to have at least a 25% deposit available. Of course, this all subject to the lender’s criteria, and the higher the LTV the higher your interest rates.

Yes, we offer SPV, Ltd Co and off-shore applications

If the intention is to run the property as a holiday let, it must generally come with alternative use as a BTL property also and as a single dwelling. Our lenders will typically still use the rental income for calculation and affordability purposes. BTL and/or current holiday let experience/accounts maybe required.

If the holiday let property doesn’t have the above, it is considered as a trading business application and 2 years full business accounts are required from the client.

This will vary case-by-case, and also between brokers and lenders. Here at Aria Finance from the initial enquiry to completion, our average turnaround time for a complex BTL is 6 to 8 weeks from initial enquiry.

How does the application process work for complex Buy-to-Let mortgages?

  • Client gets in touch with their broker seeking options to raise funds for a Buy-to-Let property.
  • Having conducted a fact-find process, the broker assesses whether a High Street Buy-to-Let mortgage will meet their needs or if they will need to refer the client’s case to a specialist lender, via a Specialist Finance Distributor (SFD)
  • If the broker decides to refer their client to a SFD, they will let their client know they are being referred and to expect a call from them directly.
  • The SFD underwriter then calls the client and assesses if the client’s circumstances will be suitable for a complex BTL mortgage. If they are, the underwriter then prepares indicative terms which they send to the client to review.
  • If the client confirms they are pleased go ahead with the full process, they are sent all relevant paperwork and a list of underwriting requirements; they can then complete the required paperwork, pay any upfront fees required, gather the required documentation and send back to the SFD.


  • The underwriter pre-underwrites the deal, ensuring it’s complete for the lender. They then send the application to the lender to get a formal approval in principle
  • The lender issues the Agreement in Principle (AIP) to the client through the SFD and requests any further supporting documents.
  • Once the client returns the required documents to the SFD, the underwriter will re-evaluate the case and instruct a valuation.
  • Once the valuation is received, the SFD packages the case and submits it to the lender.
  • The lender does a final underwrite of the loan and approve it. They then issue a formal offer, with additional documentation to sign including; the offer itself, legal charge permission and proof of buildings insurance.
  • The client signs and returns the final documents to the SFD who forwards over to the lender who instructs the solicitors when received.
  • Once all legalities have been finalised the funds are released to the borrower

Fees will vary across the market

What fees and charges can I expect with complex Buy-to-Let mortgages?

  • Broker fee – This varies between brokers. Some brokers do not charge a fee and rely on receiving commission from lenders when the loan completes. Other brokers may charge a fixed fee, or a percentage of the total loan value.
  • Application fee – Some lenders and brokers charge for submitting an application
  • Valuation fee – To calculate an unbiased, accurate value of the security, lenders will typically instruct an independent valuation. This can also include a projected valuation of the project once completed.
  • Arrangement fee – Often calculated as percentage of the total cost of the loan
  • Legal fees – If needed, borrowers will have to pay for legal costs such as hiring a solicitor or qualified legal advice
  • Exit fee – Often calculated as a percentage of the total cost of the loan. There are some commercial mortgages that do not have exit charges.
  • Administration fees - Any additional costs charged by either lender or broker


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