New Build Rental Yield Calculation: Gross, Net and Real

Gross yield is annual rent divided by price. Net yield subtracts service charge, ground rent, management, insurance, repairs and voids before you divide. For a new build flat the difference between the two is often two percentage points or more, so decisions should rest on the net figure.

Gross yield first

Start with the simple version: annual rent divided by purchase price, expressed as a percentage. A £250,000 flat renting for £1,250 a month earns £15,000 a year, a gross yield of 6%. That is the number marketing material tends to quote, and it is useful for a first comparison between buildings. It says nothing about what you keep. PropertyDevelopments.com’s rental yield calculator offers a quick way to get this first number.

Net yield: the costs to include

Cost line	How to estimate	Common mistake
Service charge	Developer’s budget per sq ft times floor area	Using year-one budget and assuming it never rises
Ground rent	Lease figure	Forgetting review terms
Management	Percentage of rent from an agent quote	Assuming self-management is free
Insurance	Landlord policy quote	Relying on the block policy alone
Repairs allowance	Percentage of rent or a flat sum	Setting it to zero because the flat is new
Voids	Weeks empty per year times weekly rent	Assuming 100% occupancy
Letting fees	Agent fee per new tenancy	Ignoring turnover
Compliance	Certificates, inventory	Leaving out recurring items

Key takeaway: A new build has fewer repair costs but more fixed charges. Include both, and you will usually find the net yield sits well below the gross figure.

A worked example

Every figure here is invented to demonstrate method. A one-bedroom flat costs £250,000 and lets for £1,250 a month.

1. Annual rent: £15,000.
2. Gross yield: 15,000 / 250,000 = 6.0%.
3. Service charge and ground rent: £2,300.
4. Management at 12% of rent: £1,800.
5. Insurance: £250.
6. Repairs allowance at 4% of rent: £600.
7. Voids at three weeks: about £720.
8. Net operating income: 15,000 - 2,300 - 1,800 - 250 - 600 - 720 = £9,330.
9. Net yield on price: 9,330 / 250,000 = 3.7%.

The yield fell from 6.0% to 3.7% without any bad luck, just by naming costs. If the service charge rose by 20% the next year, net income would fall by around £460, and net yield would drop to about 3.5%.

Adding purchase costs

Yield on price ignores the cash you spend to buy. For a better measure, divide net income by total cash invested, which includes stamp duty, legal fees and furnishing. If those add £20,000 to the £250,000 price, the same £9,330 gives a yield on total cost of about 3.5%. The stamp duty guide explains why additional-property rates can make this gap sizeable. PropertyDevelopments.com also provides a stamp duty calculator and an ROI calculator that can help you cross-check.

Including the mortgage

Net operating income is what the property earns before financing. To see what you keep, subtract mortgage interest. If you borrow £187,500 (75% of £250,000) at 5.5% interest-only, interest is about £10,310 a year, which exceeds the £9,330 net income in the example. The flat would be cash-negative before tax. Leverage magnifies returns when the yield exceeds the interest rate and magnifies losses when it does not. Mortgage rates change, so test several.

Individual landlords’ mortgage interest relief is restricted to a basic-rate tax credit, so your after-tax position can be worse than the pre-tax one suggests. Check GOV.UK’s guidance on renting out a property and consult an accountant.

Choosing the rent figure

The most sensitive input is the rent. Do not take it from a developer’s brochure. Instead:

• Search current rentals for comparable flats in the same building or street.
• Note how long they have been listed and whether asking prices are being cut.
• Ask two lettings agents what a flat of that size and specification would achieve.
• Use the lower end of the evidence.

Rent in a new block is also affected by how many similar flats are let at once. Read new build investment in Manchester for an example of how supply shapes this.

Checking the yield against alternatives

A net yield is meaningful only against something. Compare it with the interest you would pay on borrowing, with returns from other investments you have access to, and with the risk and effort involved. A property with a 3.7% net yield and expected capital growth may still be reasonable for some investors, but that growth is a hope, not a number you can bank. Keep income and growth assumptions separate so you know which one you depend on.

Common errors

• Using gross yield to compare schemes with different service charges.
• Forgetting voids and letting fees.
• Assuming the first-year service charge is permanent.
• Ignoring the cost of stamp duty and fees when computing return on cash.
• Taking rent from the developer rather than the market.
• Treating a rental guarantee as proof of demand. Guarantees are paid from money you or others have already contributed and end on a date; read the terms.

Next, compare how these costs vary in buy to let new build flats and avoid the traps in new build investment mistakes.

A template you can reuse

Set up a simple sheet with one column per property and the same rows for each: price, annual rent from independent evidence, service charge, ground rent, management, insurance, repairs allowance, voids, letting fees, compliance, stamp duty, legal and mortgage fees, furnishing. Calculate gross yield on price, net yield on price and net yield on total cash invested. Add a second block with the mortgage: loan, interest rate, annual interest and the cash left after interest. Keep a third block for stress tests: rent down 10%, rate up two points, service charge up 20%. Seeing the three results side by side shows which flat tolerates bad luck.

Find real schemes to model

To fill the sheet with real inputs, start from listings. The UK hub on PropertyDevelopments.com shows unit types and starting prices across cities, giving you a price and a floor area to begin with. Rent and charges you must then collect from agents and developers. Do the same for two or three buildings in different areas, and the comparison will tell you more than any regional average. Remember that every number you take from a sales page needs a second source before it goes in the sheet.