The difference between temporary and permanent mitigation credits 

Temporary credits are valid for a limited time from 1 January 2025 to 1 April 2030.  

Permanent credits provide mitigation over a development’s lifetime, 80 years.  

Note: Buying credits does not guarantee planning permission. Developers remain responsible for satisfying the local planning authority and any relevant competent authority that their development is acceptable.

Temporary credit arrangements 

There are new regulations for wastewater treatment works in catchments where nutrient pollution affects habitat sites. From the 1 April 2030, the new permits will take effect in Poole Harbour catchment. They will ensure lower nitrogen wastewater for some treatment works that discharge into the harbour.  

Lower nitrogen pollution in wastewater will reduce the need for mitigation. 

Natural England’s nutrient budget calculators take account of the new permitting regulations for effected treatment works.  

If the Natural England nutrient budget calculators gives two nutrient budgets for your development; a pre-1 April 2030 and one post 1 April 2030 you should consider temporary mitigation credits. 

Temporary nitrogen mitigation credits 

Buying temporary mitigation reduces the cost of delivering nitrogen mitigation measures as temporary credits are less expensive than permanent credits.  

You will need to complete you own review of the options and costs of nitrogen mitigation. 

How to calculate your credit need  

Natural England’s calculator will give you two figures. Your pre-1 April 2030 and post 1 April 2030 nutrient budgets. All calculations will be development and site specific. 

You will need your two figures from the Natural England calculator:  

• Figure 1: Your pre-1 April 2030 nitrogen budget in kilograms of total nitrogen per year (kg TN/yr ) 

• Figure 2: Your post 1 April 2030 nitrogen budget in kilograms of total nitrogen per year (kg TN/yr)  

You will need to subtract figure 1 from figure 2 to calculate your temporary nitrogen budget needs. If the calculator only gives you figure 2, you will not need temporary mitigation measures because this figure is your permanent nitrogen mitigation budget.   

Example calculation to determine temporary nitrogen mitigation budget: