What is an Annual Investment Allowance (AIA)?

A limited company HMO mortgage is a specialist buy-to-let mortgage where the borrowing entity is a registered UK limited company rather than an individual. Since tax changes introduced in 2017 (Section 24 of the Finance Act 2015), which phased out the ability for individual landlords to deduct mortgage interest in full from rental income, there has been a significant shift toward purchasing and refinancing HMOs through limited company structures — most commonly Special Purpose Vehicles (SPVs) set up specifically to hold property. The key advantage is that a limited company can still deduct 100% of mortgage interest as a business expense before calculating corporation tax, unlike individual landlords who are now restricted to a 20% basic rate tax credit. This makes the limited company route particularly attractive for higher or additional rate taxpayers. The mortgage itself works similarly to a personal HMO mortgage: the lender assesses the company's ability to service the debt based on rental income, applies a stress test, and requires a minimum deposit (typically 25-30%). The main differences are that rates are generally 0.5-1% higher than personal mortgages, the lender will require personal guarantees from the directors, and company accounts or a business plan will be needed if the company is newly formed. Most lenders require the company to have an SIC code of 68100 or 68209 (property rental activities). If you are considering whether to buy in personal name or through a limited company, always take personalised tax and legal advice first, as the decision depends on your income level, portfolio size, and longer-term strategy.

Limited company HMO rates are often similar to personal ownership at the same LTV, though the best deals depend on trading history, director guarantees, and rental stress tests. Some lenders add a small premium (typically 0.1–0.3%) for newer SPVs with no track record. The real saving is usually tax efficiency — mortgage interest remains deductible in the company, unlike personal Section 24 restrictions. Compare net cost after corporation tax and dividend tax, not just the headline rate.