The South East's 5.3% yield hides a £431 monthly loss

You've done well out of your Yorkshire portfolio, and now someone at a landlord meetup has told you the South East is "safer money": wealthy commuter towns, strong long-term demand, none of the boom-bust swings you get further north. It sounds sensible right up until you actually run the numbers on a typical South East property, and the numbers say something rather different.

A property bought today at the South East's regional average price of £376,819 yields just 5.3% gross, and once a buy-to-let mortgage, running costs and the Section 24 tax rules are applied, a higher-rate taxpayer is left roughly £431 a month out of pocket (Land Registry HPI, April 2026; Zoopla / PropertyInvestmentsUK regional yield tracker, 2026). That's not a rounding error. It's a portfolio decision.

What £376,819 actually buys you in the South East

The South East is England's second most expensive region after London, with an average house price of £376,819 as of April 2026, up just 0.3% over the year (Land Registry HPI, April 2026). That's roughly 36% above the UK national average of £277,484 (Nationwide HPI, June 2026). Within the region, first-time buyer prices vary sharply: £387,000 in Guildford, £304,000 in Reading and £343,000 in Brighton and Hove, all as of April 2026 provisional data (ONS / Land Registry).

High prices don't just squeeze buyers looking for a home; they squeeze the maths on every rental purchase too. The South East is also where 51% of first-time buyers now pay some Stamp Duty Land Tax at all, second only to London's 79.7%, against a national picture where most Northern regions sit in the single digits (Zoopla H1 2026 buyer enquiry analysis, published 9 July 2026).

So if you're comparing a South East purchase against topping up an existing Northern portfolio on price alone, you're paying significantly more for a similar-sized property before you've even checked what it will actually rent for.

The cash flow maths: a £431 monthly loss once tax is applied

Take a property at the regional average price of £376,819, bought with a 75% loan-to-value buy-to-let mortgage: a £94,205 deposit and a £282,614 loan. At the current average buy-to-let fixed rate of 5.42% (Moneyfacts, 1 July 2026), that's £1,276 a month in interest on an interest-only basis, the standard structure for most buy-to-let lending.

At the region's 5.3% average gross yield, that property rents for around £1,664 a month. Strip out a 12% management fee (£200), a one-month annual void allowance (£139) and a modest insurance and maintenance reserve (£70), and the property is already roughly £21 a month underwater before any tax is due.

Then Section 24 arrives. Because mortgage interest can no longer be deducted as a business expense, a landlord pays income tax on the full rental income and claims only a 20% credit against the interest paid. For a higher-rate (40%) taxpayer, that's an additional £410 a month in tax, taking the total monthly loss to £431, or £5,172 a year, just to hold the property. A basic-rate (20%) taxpayer fares better but still loses around £98 a month, because the 20% credit barely offsets a 20% tax charge on a much larger gross income figure.

So if you're a higher-rate taxpayer weighing up a South East purchase at anything close to the regional average yield, you're not looking at modest underperformance. You're looking at funding over £5,000 a year out of your own pocket to hold it.

Stamp duty adds another £27,682 before you've collected a penny in rent

The South East sits entirely in England, so Stamp Duty Land Tax applies here, not Scotland's Land and Buildings Transaction Tax or Wales's Land Transaction Tax. Additional residential properties, including every mortgaged buy-to-let purchase, carry a 5% surcharge on top of the standard bands, raised from 3% on 31 October 2024 at the Autumn Budget. On the regional average price of £376,819, that means 5% on the first £125,000, 7% on the next £125,000 and 10% on the remaining £126,819, a total bill of £27,682.

Run that against the monthly cash flow loss calculated above and the stamp duty bill alone is worth more than five years of the ongoing shortfall, paid in full before the first month's rent has even landed. Anyone weighing a South East purchase should run their own numbers through our stamp duty calculator and our Section 24 tax calculator before making an offer, because the surcharge alone can be the difference between a deal that pencils and one that doesn't.

So before this property has paid you a single month's rent, the upfront tax bill has already cost more than half a decade of the ongoing loss combined, which makes the purchase price only half the story.

Where the region's average yield numbers hide the exceptions

Regional averages flatten a lot of variation. Southampton's SO17 postcode, driven largely by student and young professional demand near the university, delivers gross yields of roughly 7.5% to 9.0%, and Portsmouth's PO4 postcode clears around 7.0% (PropertyInvestmentsUK, 2026). Both comfortably beat the 5.3% regional average and would flip the cash flow calculation above from a loss into a modest profit even after tax. The catch is that these are specific, lower-priced postcodes with strong rental demand drivers, not a description of the South East as a whole.

Compare that with the North East, where the average yield across the whole region already sits at 9.8%, the highest in the UK, without needing to cherry-pick a single postcode (Fleet Mortgages Q1 2026 Rental Barometer). Other regions including Yorkshire and the Humber, the West Midlands, the North West, Wales and the East Midlands all average above 8% (same source). Our earlier look at marketed yield claims that don't hold up citywide found a similar gap between the headline number an agent quotes and what the region actually delivers.

So the message isn't "avoid the South East entirely." It's that buying at the regional average is exactly where the numbers turn against you, and the calculation above only works in your favour if you can identify, and verify, a specific postcode clearing close to 7% gross rather than trusting the regional headline.

The EPC bill still due by 2030

The South East's housing stock skews older than many Northern cities, with a large share of pre-1980s commuter-belt and heritage housing that tends to sit at lower Energy Performance Certificate ratings. Every privately rented home in England and Wales will need to reach at least an EPC C rating by 1 October 2030, a single deadline covering existing tenancies as well as new ones, with a cost cap of £10,000 per property and fines of up to £30,000 per breach for non-compliance (Warm Homes Plan, GOV.UK, published 21 January 2026, subject to final legislation). Average compliance spend is running at roughly £6,900 per property based on current upgrade costs.

Bolt a £6,900 upgrade bill onto a purchase that is already losing £431 a month for a higher-rate taxpayer, and the payback period on that particular South East property stretches out considerably further than the headline yield would suggest. This is exactly the kind of cost that a 5.3% regional yield doesn't leave much room to absorb.

So if you're assessing an older South East property specifically, check its current EPC rating and the realistic upgrade cost before you factor it into your yield calculation, not after you've exchanged contracts.

What this means for you

If you're weighing a South East purchase against topping up your existing portfolio elsewhere, the maths points toward one of two moves. Either concentrate any new South East capital specifically in a postcode clearing 7% or more gross, verified against actual comparable rents in that street rather than a regional average, or redeploy that capital into a region where the average yield already clears 8% without hunting for exceptions, such as the North East at 9.8%. Buying at the South East's regional average price and hoping Section 24 doesn't bite is, frankly, the one option the numbers rule out for a higher-rate taxpayer. If you're already holding property in the South East and haven't checked its yield against these figures recently, that's worth doing before your next remortgage, not after: a fixed rate renewal is the natural moment to stress test whether the property still earns its place in the portfolio at today's rates and today's tax rules, rather than the rates and rules that applied when you bought it. For the wider incorporation question this raises for larger portfolios, our piece on incorporating into a limited company and our earlier Section 24 breakdown both walk through the trade-offs in more detail.