Pass through (pass-through charges)

What it is

In a pass-through contract, the supplier fixes the energy part of your price but passes certain third-party costs on to you as they change. Which costs are passed through varies by supplier and contract, but they are usually network and policy costs, such as TNUoS, DUoS and BSUoS. A fully fixed contract is sometimes called non pass through.

Where you will see it

• On quotes, where unit rate and "non-commodity" costs are shown separately.
• In contract terms and the Principal Terms, which should list exactly which charges can change.
• On bills as separate lines for each passed-through cost.

Why it matters

Pass-through prices usually look cheaper at the start, because the supplier does not have to build in a margin for cost changes. The trade-off is uncertainty: when network charges rise, so does your bill. A pass-through quote and a fixed quote are not like for like, so compare both on total estimated cost. Our guide to pass-through vs fixed charges goes through what to ask.

Example

Quote A is fixed at 28.0p/kWh including everything. Quote B is 24.0p/kWh plus passed-through charges currently worth about 3.5p/kWh, a total of 27.5p/kWh today. If those charges rise by 1p, Quote B costs 28.5p, which is more than A. On 20,000 kWh that is 20,000 x £0.005 = £100 a year worse than A. The numbers are illustrative.

Ask what the passed-through costs were last year, and whether the contract caps increases.

Related terms

See non-commodity charges and contract terms to check.