Southern England's Rate Cut (SSEN) Might Cost You More. Here's the Maths.

SSEN's 2027-28 DUoS charges are now published. If your business is in southern England or northern Scotland, this affects you directly. SSEN operates SEPD across Hampshire, Berkshire, and Oxfordshire, and SHEPD from the Highlands to Orkney and Shetland — and their new DUoS tariffs tell very different stories. The southern England headline looks good: the domestic peak rate is down -7.4%. Look closer, though. The amber and green rates rose, and the fixed charge more than doubled. For most customers, that is not a price cut.

Lower Rate, Higher Bill?

In southern England (SEPD), the domestic red rate drops from 14.017 to 12.981 p/kWh — a -7.4% reduction. But the amber rate rose +13.8% and the green rate rose +63.2%. And the fixed charge jumps from 5.28 to 11.04 p/MPAN/day — a +109% increase.

The fixed charge increase alone adds roughly £21/year for every domestic customer across the SEPD region — from Southampton to Reading to Oxford — regardless of how much electricity they use. The unit rate changes are mixed — the peak rate fell, but off-peak rates both rose — so any saving on the volumetric side is modest at best.

For most domestic and small commercial customers, the net effect is higher annual charges.

"In southern England, the peak rate fell 7.4%. But amber and green rates rose. The fixed charge more than doubled. The £21/year increase in standing charges alone outweighs any unit rate saving for the vast majority of customers."

For southern England in 2027-28, the net effect is a shift in how charges are collected — less from peak volumetric rates, more from the daily fixed charge. The total revenue the network recovers stays roughly the same. But for most customers, that rebalancing means higher bills.

Meanwhile, in the Highlands...

In Scotland (SHEPD), the changes are more straightforward. Charges increase across the board:

• Domestic red rate: 11.447 → 13.849 p/kWh +21%
• Domestic fixed charge: 11.77 → 16.17 p/MPAN/day +37%
• Capacity charges: +15–21% across bands

The SHEPD region — covering northern Scotland from Perth and Aberdeen to Inverness, plus Orkney, Shetland, and the Hebrides — already has some of the highest distribution rates in Great Britain. It spans 25% of GB's landmass with an estimated 740,000 customers and over 100 subsea cables to island communities. When your network costs that much to operate, cost-reflective charging produces significantly higher charges.

What This Means for a Typical Business

Take a typical non-domestic customer in each region — 60,000 kWh per year on the standard Band 1 tariff. Here's what they'd pay in annual DUoS charges:

The Charges That Appeared from Nowhere

Several SSEN tariffs that were previously zero — suppressed under one-off Ofgem derogations — have snapped back to real charges for 2027-28:

• SEPD HV_SS_B1 fixed charge: 0 → 188.01 p/MPAN/day — that's £686/year in charges that were zero last year
• SEPD HV_SS_B4 red rate: 0 → 3.725 p/kWh
• SHEPD HV_SS_B4 red rate: 0 → 1.707 p/kWh (a reversion — this rate was 1.721 in 2025-26 before the derogation suppressed it)

Band 4 red rates across southern England see some of the sharpest increases: LV_SS_B4 red rate up +56%, LVS_SS_B4 red rate up +72%. These are higher-capacity non-domestic connections, and the snap-back from derogation-suppressed rates is significant.

The regulatory driver is DCP 450 — a DCUSA change proposal accepted by Ofgem in October 2025. It replaces ad-hoc derogations with a permanent mechanism for handling surplus residuals within the CDCM framework (Schedule 16), and takes effect from 1 April 2027.

The Two-Year Picture

Year-on-year figures tell part of the story. Here's what happens when you compare against what you're paying today (2025-26) — the rates currently on your bill right now.

Over two years, annual DUoS charges for a typical 60,000 kWh business have risen by £200 in southern England and nearly £500 in Scotland. The pattern is consistent across tariffs — charges are being rebalanced from unit rates to fixed charges, and derogation-suppressed rates are snapping back. SSEN's 2027-28 rates are now in EnergyCode.