Low-EPC-rated properties, D, E, and especially F and G, tend to sell for less than equivalent higher-rated stock nearby. That discount is real, and so is the reason for it: whoever buys the property either has to accept a currently-compliant-but-possibly-not-by-2030 EPC E, or budget for upgrade work to get it to C. Neither of those is automatically a bad deal, it depends on the actual numbers.
The two things that decide it
A cheap, low-EPC property is worth buying as an investment when the discount on the purchase price is larger than the realistic cost of the upgrade work, once you also account for the yield it generates in the meantime. It's not worth it when the discount barely covers the upgrade cost, or when the property's yield is mediocre even before you factor in a five-figure retrofit bill.
That means the decision comes down to two numbers you should actually check, not estimate by feel: what the property would rent for, and what upgrading it would realistically cost.
Checking the yield side
A postcode district's current average buy price, rent, and gross and net yield are on every area page, based on live market listings rather than asking-price guesses. If a specific low-EPC property is priced well below its area's average for a comparable type, that's the discount worth quantifying, and the area page tells you what a realistic yield looks like once you factor that discount in.
Checking the upgrade cost side
The proposed EPC C minimum from October 2030, and its £10,000 cost cap, are covered in full in our explainer on the EPC C rules. For a quick estimate on a specific property, the EPC C upgrade cost calculator gives a rough range based on the current rating and property type, capped at the proposed £10,000 limit.
Putting it together
Run the numbers before assuming either way. A £15,000 discount on a property that would cost £6,000 to bring to C, in an area with a genuinely good yield, is a real opportunity that a lot of buyers will overlook simply because "low EPC rating" sounds like a red flag by default. Equally, a small discount on a property that would cost close to the £10,000 cap to upgrade, in an area with a mediocre yield to begin with, is a worse deal than it looks once you actually total it up.
The honest answer to "should you buy a low-EPC buy-to-let" is: check the specific property's numbers, not the general reputation of low-EPC properties as a category.
Figures referenced are gross averages from live market listings and general cost estimates as of publication, not a valuation of any individual property. Not financial advice.