Buy-to-Let Through a Company or in Your Own Name: Modelling the Real Difference
Whether a buy-to-let is held personally or through a company changes the tax treatment of the mortgage interest, the rate applied to profits, and the cost of taking money out or selling up. For a higher-rate taxpayer with a mortgage, personal ownership restricts interest relief to a basic-rate tax reducer, while a company generally deducts interest as a business expense before corporation tax. The difference is not fixed: it depends on borrowing level, the owner's marginal rate, and how and when value is extracted.
How interest relief differs between the two routes
For personally held property, finance cost relief is restricted. A landlord cannot deduct mortgage interest from rental income in the normal way; instead the interest generates a tax reducer worth a set percentage of the finance cost, and that reducer is capped. The practical effect is that the tax reducer is most valuable to those on lower marginal rates and least valuable to higher and additional-rate taxpayers, because the relief is given at the basic rate rather than at the landlord's own marginal rate.
For a company, the position is different in mechanics rather than in principle. Interest is treated as an ordinary business expense, deducted from rental income before the taxable profit is calculated. That means the deduction is effectively relieved at the corporation tax rate applying to the company's profits, not at the individual's marginal income tax rate. A landlord must confirm the current rates and any restrictions with the relevant authority for the specific property and borrower.
The gap between the two routes therefore widens as borrowing rises and as the individual's marginal rate rises. A cash purchase produces no interest to relieve, so the relief question largely disappears and the comparison shifts to the rate applied to profits and the cost of extraction.
Corporation tax versus income tax mechanics
Under personal ownership, rental profit after allowable expenses is added to the landlord's other income and taxed at their marginal income tax rate. That can push the landlord into a higher band, and it can also affect personal allowances and the tax charged on other income. The interaction with the rest of an individual's affairs is part of the modelling, not an afterthought.
Under company ownership, the company pays corporation tax on its profits at the rate applicable to that company. Profits retained in the company are taxed once at that level; profits distributed to the shareholder are then subject to further tax on the dividend, subject to the dividend allowance and the rates in force. The company route therefore defers rather than removes the second layer of tax where money is taken out.
Losses, capital allowances, and the treatment of replacement of domestic items can also differ between the two routes, and the availability of reliefs depends on the facts. A landlord must confirm the position with the relevant authority for the specific property rather than assume the mechanics carry across unchanged.
Modelling the same property both ways
A workable model starts with gross rent, subtracts running costs, and then applies the two tax mechanics side by side. Using asking rents collected from live rental listings, the median of area medians in our sample was £700 per calendar month for a 1-bed across 10 areas, £1,100 for a 2-bed across 16 areas, £1,250 for a 3-bed across 7 areas, and £1,100 for a 4-bed in a single area. These are asking prices, not achieved rents, and should be treated as a starting assumption only.
The table below sets out the sequence of the calculation rather than a result, because the outcome depends on the individual's marginal rate, the company's applicable rate, and the level of borrowing.
| Step | Personal ownership | Company ownership |
|---|---|---|
| Gross rent | Rent received | Rent received |
| Running costs | Deducted as allowable expenses | Deducted as allowable expenses |
| Mortgage interest | Not deducted from rental income; generates a tax reducer at the basic rate, subject to a cap | Deducted as a business expense before tax |
| Tax on profit | Income tax at the individual's marginal rate | Corporation tax at the company's applicable rate |
| Taking money out | Already taxed as income; no further extraction step | Dividend or salary, with further tax due on distribution |
| Exit | Capital gains tax on the individual, with any available reliefs | Tax on the gain within the company, then further tax on extracting the proceeds |
Run the model at more than one borrowing level. At low or zero borrowing, the interest relief difference is small or absent, and the comparison turns on the rate applied to profit and the extraction cost. At high borrowing, the personal route's restricted relief becomes a larger drag for a higher-rate taxpayer, while the company route deducts the full interest before tax but adds a second layer when profits are distributed.
Refinancing and extraction
Refinancing a personally held property does not create a tax event in itself, but the use of the borrowed money matters. Interest on borrowing used for the property's purchase or improvement is finance cost; borrowing taken out for personal purposes is not, and the relief position must be checked against how the funds are applied. A landlord must confirm the treatment with the relevant authority for the specific property.
Refinancing inside a company raises a different set of questions, including whether the company can service the debt, how the interest is treated in its accounts, and how any extracted cash is characterised. Money moved from the company to the shareholder is not a free transfer; it is either remuneration, a distribution, or a loan, and each has its own tax consequences.
Extraction is where the company route's headline rate advantage can narrow. If profits are left in the company, only corporation tax applies at that stage. If they are drawn out, the dividend or salary tax is added on top, and the combined burden can approach or exceed the personal route depending on the amounts and the individual's other income.
Exit costs and which route suits which borrowing level
On exit, a personally held property produces a capital gain in the individual's hands, with reliefs and the annual exempt amount applied to the individual. A company-held property produces a gain within the company, taxed at the company's rate, and then a further cost when the proceeds are extracted. The company route can therefore carry a higher total exit cost where the intention is to spend the money rather than reinvest it.
As a broad modelling pattern rather than a recommendation: with little or no mortgage, the interest relief difference is minimal, and the choice turns on the rate applied to profits, the extraction plan, and the exit intention. With substantial mortgage interest and a higher-rate individual, the restricted personal relief is a larger factor, and the company route's full interest deduction becomes more material. With profits retained for reinvestment, the company route defers the second layer of tax; with profits drawn annually, that deferral is lost.
Each case turns on the numbers, the borrower's other income, and the plan for the property. A landlord must confirm the current rates, thresholds, and reliefs with the relevant authority for the specific property before relying on any model.
What to check next
- Confirm the current finance cost relief rules and cap with the relevant tax authority, and check how they apply to the specific property and borrower.
- Confirm the corporation tax rate applicable to the company and the dividend or salary rates on extraction, using the authority's current published rates.
- Check the capital gains position on exit for both routes, including available reliefs and the annual exempt amount, against the authority's guidance.
- Build the model with gross rent, running costs, mortgage interest, and the tax step for each route, then repeat it at low, medium, and high borrowing levels.
- Verify achievable rent against public sale-price records and live listings rather than relying on asking figures alone, and check the energy certificate register for the property's rating.
- Confirm the treatment of any refinancing or extracted cash with the relevant authority before drawing funds.