Quick answer: credits needed = the nutrient budget in kg/yr (after the ×1.2 buffer), taking the higher of the pre-2030 and post-2030 figures; cost = credits × the scheme's price per kg. Published prices range from about £3,000 per kg of nitrogen (Poole Harbour, Tees, the Solent's permanent credit) to £28,000–£50,000 per kg of phosphorus (Cumbria's rivers, the Somerset Levels, the Itchen).
Credits and cost
Type the price you have been quoted. Choosing a catchment with a published price fills it in.
Budgets already include Natural England's 20% precautionary buffer if they came from the NE calculator or NutrientMonkey. Prices shown are the published scheme figures on our catchment pages at the date of writing; credit availability and price change, so confirm with the scheme before you rely on a figure.
How credits are counted
A nutrient neutrality assessment ends in a number: the kilograms of nitrogen or phosphorus a year the development adds to the protected water, after the wastewater load, the land-use change, any sustainable drainage credit and the ×1.2 precautionary buffer. If it is above zero, that number is the mitigation you must secure before permission — and the unit of mitigation is the credit, one kilogram of the nutrient per year, held in perpetuity by a scheme that has taken an equivalent load out of the catchment: land out of agriculture, a wetland, an upgraded treatment works.
Where the wastewater treatment works your scheme drains to has a permit that tightens on 1 April 2030, the budget comes in two figures. The post-2030 figure is usually lower, and your mitigation has to cover the higher one — which is why the calculator asks for both and takes the maximum. Some schemes split the answer into a cheaper temporary credit for the years before the upgrade and a permanent credit for the load that remains afterwards.
Published credit prices
These are the schemes that publish a price per kilogram; every other catchment is priced by quotation. Our catchment pages carry the detail and the date.
| Catchment | Nutrient | Permanent credit (£/kg/yr) | Temporary credit (£/kg/yr) |
|---|---|---|---|
| Poole Harbour | N | £3,250 | — |
| Solent | N | £3,250 | £325 |
| Tees (Teesmouth) | N | £2,700 | — |
| Somerset Levels & Moors | P | £34,061 | — |
| River Itchen | P | £50,000 | — |
| Derwent & Bassenthwaite | P | £28,000 | £10,000 |
| River Eden | P | £28,000 | £10,000 |
| River Kent | P | £28,000 | £10,000 |
| River Lugg | P | £14,000 | — |
| Esthwaite Water | P | £28,000 | £10,000 |
Before you buy: the four ways to need fewer
Credits are the expensive end of the process, so the budget is worth challenging first. Occupancy and water use: the standard 2.4 persons and daily allowance are conservative for one-bedroom flats and for schemes with a 110-litre planning condition. Land use: fertilised arable land coming out of production is a negative term that offsets wastewater load, and the export coefficients are catchment-specific. Drainage: SuDS designed and evidenced for nutrient removal earns a credit against the land-use term. Treatment: a package plant with better nutrient removal than the works cuts the wastewater load directly. All four are inputs in NutrientMonkey, free; where the case is harder than the calculator, our nutrient neutrality assessment service prepares it and sizes the mitigation.
Frequently asked questions
How many nutrient credits do I need?
As many kilograms per year as your nutrient budget shows above zero, after the 20% precautionary buffer: a budget of 4.2 kg/yr of nitrogen needs 4.2 credits. Where the treatment works' permit tightens in April 2030 the budget has two figures, and the mitigation has to cover the higher of them. One credit is one kilogram of the nutrient per year, secured in perpetuity.
How much does a nutrient credit cost?
It varies by catchment and by scheme, from a few hundred pounds per kilogram of nitrogen in some Solent temporary schemes to tens of thousands per kilogram of phosphorus in the Somerset Levels or the Itchen. Our catchment pages carry the published price where a scheme quotes one; where no price is published you will need a quote from a provider, and this calculator lets you type the figure in.
Why does the calculator ask for two budgets?
Because many catchments have a wastewater treatment works whose permit tightens on 1 April 2030 under the Levelling-up and Regeneration Act. Natural England's calculators give a pre-2030 and a post-2030 budget for those sites; the post-2030 figure is usually lower, and the mitigation you secure now must cover the higher of the two for as long as it applies.
What is the difference between temporary and permanent credits?
Some schemes sell a cheaper temporary credit that covers the period until the treatment works upgrade, alongside a permanent credit that covers the load remaining afterwards. Where a scheme publishes both, the calculator shows the temporary price as a note; the cost shown uses the permanent price, which is the one that has to be secured in perpetuity.
Can I reduce the number of credits instead of buying them?
Often. Sustainable drainage designed and evidenced for nutrient removal earns a credit against the land-use term; a package treatment plant with better nutrient removal than the works cuts the wastewater load; taking fertilised land out of production within the red line counts as land-use change; and getting the occupancy and water-use assumptions right removes conservatism. Run the alternatives in the free calculator before you price credits.
Will the Nature Restoration Fund replace credits?
In catchments where an Environmental Delivery Plan is in force, a developer will be able to pay the Nature Restoration Levy instead of securing bespoke mitigation. Until an EDP covers your catchment the existing process applies: a nutrient budget, and credits or on-site mitigation secured before permission is granted.
Start from the budget: the free nutrient neutrality calculator · the policy background: the Nature Restoration Fund · all 27 catchments on one page: the building regulations reference.