Gross vs Net Rental Yield: The Maths Listings Hide (2026)

You see "6% rental yield" on an investment listing and do the sum: £500,000 × 6% = £30,000 a year. It sounds great. But that figure does not tell you what actually reaches your pocket — because it includes neither the costs nor the purchase expenses. This guide shows the real calculation professionals use, step by step, and explains why gross yield is a marketing number.

Two Formulas, Two Different Realities

The difference sits in two simple formulas:

Gross yield = (Annual rent ÷ Property price) × 100

Net yield = ((Annual rent − Annual costs) ÷ Total purchase cost) × 100

There are two changes, and both lower the yield. The first is obvious: you deduct the costs. The second is the point most investors miss: the denominator is not the "property price" but the "total purchase cost". That is, you count the stamp duty, legal fees, survey and mortgage arrangement fees as part of your capital too — because that money also left your pocket.

For a foreign investor, the second point stings especially: stamp duty alone can exceed 10% of the property price (see our stamp duty guide). That enlarges the denominator and lowers the real yield.

Which Costs Are Deducted?

Here is the list the listings do not show you. Typical annual costs on a buy-to-let property:

Three items in particular surprise new investors:

The service charge is a cost that directly eats your net yield on a leasehold London flat and one you do not control; it can rise on the building management's decisions. Always request the last three years' service charge history before making an offer.

Void risk has increased since the Renters' Rights Act came into force on 1 May 2026: because fixed-term tenancies have gone, your tenant can leave at any time on two months' notice. If you do not build a realistic void reserve into your annual figures, your model collapses.

Tax never appears in most gross yield calculations. If you are a landlord living abroad, 20% is deducted from your rent under the Non-Resident Landlord Scheme (or you declare it via Self Assessment). Individual landlords also cannot deduct mortgage interest in full, because of Section 24.

A Worked Example: What Is a "6% Yield" Really?

Let us build an example. Note: the cost figures below are assumptions for illustration only; real figures vary greatly by property, building and area. You must gather the real figures for your own property.

Scenario: an investor living abroad buys a £500,000 London flat; the annual rent is £30,000 (£2,500 a month).

Step 1 — What the listing shows (gross): £30,000 ÷ £500,000 = 6.0% gross yield

Step 2 — Calculate the real capital (the denominator):

Step 3 — Deduct the annual costs:

Step 4 — Calculate the net yield: Net yield = (Net rental income ÷ £555,000) × 100

Whatever the result, the mechanics are clear: you shrink the numerator (costs) and enlarge the denominator (purchase costs). Together, these two movements pull the gross figure you saw in the listing markedly downwards. And this is still before tax.

Leverage, ROI and the Right Comparison

One point must be clear: the calculation above shows the unleveraged (mortgage-free) return and measures the performance of the *property itself*. If you use a mortgage, there is a second figure to look at: the cash-on-cash return (ROI). This divides your annual net cash profit (rent − all costs − mortgage interest) by the *actual cash that left your pocket* (deposit + stamp duty + all purchase costs).

Leverage is a sword: it raises your cash return if the rent exceeds your mortgage cost; it turns it into a loss if it does not. And remember: as an individual landlord you cannot deduct your mortgage interest in full for tax (because of Section 24) — which can seriously damage the after-tax return of a leveraged personal investment.

One final honesty: a high yield does not always mean a good investment. The highest gross yields are usually found in the areas with the lowest capital growth potential and the highest management risk. An investment decision looks at the balance between yield and capital growth — not at a single number.

Optivest Note: This sits at the centre of Optivest's real service area. The job of our investment consultancy service is not to tell you a gross yield figure but to help you gather the real numbers: what is that building's service charge history over the last three years, what is a realistic void rate in the area, what will management cost, what is your total capital including stamp duty? Our property management service actually runs some of these costs (management, maintenance, compliance) and therefore holds real cost data. Let us say it plainly: be sceptical of anyone trying to sell you a property on a gross yield — and that applies to our projects too. The right question is not "what is the gross yield?" but "what reaches my pocket after all costs and tax?"

Important notice — not financial/tax advice: This article is for general information only. The figures here are illustrative assumptions and do not represent the real return of any property; cost items vary greatly by property, building and area. Past or projected returns are no guarantee of future returns. For investment decisions consult an independent, regulated financial adviser (IFA); for the tax calculation consult a qualified tax adviser. Optivest is not a licensed financial adviser and does not provide tax advice.

Frequently Asked Questions

What is the difference between gross and net yield?

Gross yield = annual rent ÷ property price; it includes no costs or purchase expenses and is the figure shown in listings. Net yield = (annual rent − annual costs) ÷ total purchase cost; it deducts the costs and adds stamp duty and legal fees into the capital. Only net yield shows the real performance.

Which costs must I account for?

Service charge (usually the largest item on leasehold), ground rent, property management fee (~10-15% of rent + VAT), insurance, a maintenance/repairs reserve, a void reserve, and tax (the 20% NRL withholding for overseas landlords). Safety certificates (EICR, gas) are regular costs too.

Why does stamp duty affect the yield?

Because it is part of your real capital. When calculating net yield, the denominator should be the "total purchase cost", not the "property price". Since stamp duty can exceed 10% of the property price for a foreign investor, this correction lowers the yield markedly.

How much should I set aside for voids?

This depends on the area and the property, but a prudent reserve is essential — and the risk has risen since the Renters' Rights Act of 1 May 2026: your tenant can leave at any time on two months' notice. A calculation that assumes zero voids is not realistic.

Is a high yield always good?

No. The highest gross yields are usually found in the areas with the lowest capital growth potential and the highest management risk. A good investment decision looks at the balance between yield and capital growth, and at the real net figure — not at a single gross percentage.

In Summary, and How to Reach Us

The rental yield you see in listings is a marketing figure: it includes neither the costs nor the purchase expenses. The real calculation works in two directions — it deducts the costs (service charge, management, insurance, maintenance, voids, tax) and adds the purchase costs into the denominator (including stamp duty exceeding 10% for a foreign investor). The result is a net yield markedly lower than the listing shows.

Optivest's investment consultancy service helps you gather the real numbers rather than telling you a gross figure; our property management service holds the real data on these costs. Contact us or reach us on WhatsApp. See our investment consultancy service, our property management service, and our stamp duty calculator to test the purchase cost.