T23: aerobic composting
Source: gov.uk (2025-07-01)

T23 exemption allows you to compost small volumes of vegetation, cardboard and food waste to spread on soil to add nutrients or improve the structure.

There’s a charge for most waste exemptions

This exemption is in band 2. Read waste exemption charges (https://www.gov.uk/government/publications/waste-exemptions-how-to-choose-register-and-pay/waste-exemption-charges) to find out what the charges and charging bands are.

You can also treat the waste, before you compost it, by chipping or similar activities.

Types of activity you can carry out

These include:
- a school composting kitchen and garden waste in its grounds
- an allotment association composting their old plants and trimmings
- a community composting group bringing locally produced vegetable peelings and garden waste to a central point for composting before it is used back in local gardens
Types of activity you cannot carry out

You cannot:
- purposely treat the waste in the absence of oxygen (anaerobically) – see related exemptions (#RE23)
- treat waste not listed under this exemption
- treat waste that is an animal by-product unless you have appropriate authorisation
Types of waste you can treat

The types of waste you can treat under this exemption can be grouped into 2 tables. These show the maximum quantities you can use and conditions for using the specific types of waste.

The waste codes are those listed in the List of Wastes (LoW) Regulations. You need to make sure your waste fits within the relevant waste code and the description in the table.

Table 1

You can store any of the waste in table 1 for up to one month before treatment.

Table 2

For waste in table 2 you can:
- treat up to 10 tonnes in total of this waste at any time
- store it for up to 7 days before treatment
After treatment you can store the compost for up to 12 months, but this is included in the total quantity that can be stored or treated.

Quantity of waste you can treat

There are 2 separate limits for the amount of waste you can store or treat at a place at any one time.

You can store or treat up to 80 tonnes of waste at any one time if you compost and use the waste in the same place it was produced.

This could apply to a large estate such as a National Trust property, a plant nursery or an allotment association.

You can store or treat up to 60 tonnes of waste at any one time if you:
- bring waste from other places to the place where it will be composted
- use the compost somewhere other than where it was composted
This could apply to an allotment association or a community composting group.

Key conditions

The treatment must produce a stable sanitised material (see compost definition) that can be spread onto land to add nutrients or improve the soil structure.

Other things you should know

Associated prior treatment in this exemption means screening, chipping, shredding, cutting, pulverising or sorting waste for aerobic composting.

Composting can be done in open windrows, in heaps that are turned regularly or in small closed vessels (known as in-vessel composting (IVC)).

Composting is an active process and you must maintain the right conditions to prevent the treatment becoming anaerobic as this would lead to odours and poor compost being produced.

There is a composting industry code of practice which you can find on the Organics Recycling Group website (http://www.organics-recycling.org.uk/page.php?article=1749&name=The+Composting+Industry+Code+of+Practice).

Animal by-products Regulations – animal by-products can include 020202 animal tissue waste or catering waste from kitchens and restaurants (200108 biodegradable kitchen and canteen waste).

If you are intending to compost animal by-products you may also need approval from the Animal and Plant Health Agency (APHA) (https://www.gov.uk/government/organisations/animal-and-plant-health-agency). You are particularly likely to need APHA approval if you intend to supply compost to other users or use the compost at another place.

You have to exclude farmed animals (includes pet sheep, cattle, pigs or poultry) from the area where the composting takes place and where the compost will be used.

For further information on animal by-products requirements, see APHA’s guidance (https://www.gov.uk/government/collections/guidance-for-the-animal-by-product-industry).

Compost quality protocol (https://www.gov.uk/government/collections/quality-protocols-end-of-waste-frameworks-for-waste-derived-products) – working with WRAP (Waste & Resources Action Programme) the Environment Agency has developed a quality protocol for producing compost from different types of segregated biowaste, including food and garden waste. The aim is to help you produce compost that would not need to be classified as waste.

If you comply with the compost quality protocol and produce a compost that complies with the PAS 100 standard, the Environment Agency would not consider the compost as waste.

Related exemptions

T24 – anaerobic digestion at premises used for agriculture and burning of resulting biogas (https://www.gov.uk/guidance/waste-exemption-t24-anaerobic-digestion-at-premises-used-for-agriculture-and-burning-resulting-biogas).

T25 – anaerobic digestion at premises not used for agriculture and burning of resulting biogas (https://www.gov.uk/guidance/waste-exemption-t25-anaerobic-digestion-at-premises-not-used-for-agriculture-and-burning-resulting-biogas).

U10 – spreading waste to benefit agricultural land (https://www.gov.uk/guidance/waste-exemption-u10-spreading-waste-to-benefit-agricultural-land).

U11 – spreading waste on non-agricultural land (https://www.gov.uk/guidance/waste-exemption-u11-spreading-waste-to-benefit-non-agricultural-land).

Register this exemption

You need to register this exemption (https://www.gov.uk/guidance/register-your-waste-exemptions) with the Environment Agency if you meet the requirements.

Related permits

If you want to compost more waste than is allowed under this exemption, you will need to apply for an environmental permit (https://www.gov.uk/guidance/waste-environmental-permits).

Definitions

Aerobic composting – decomposing biodegradable waste using bacteria, yeast and fungi that need oxygen to produce compost.

Catering waste – all waste food, including used cooking oil originating in restaurants, catering facilities and kitchens, including central kitchens and household kitchens.

Compost – a solid particulate material that is the result of composting, which has been sanitised and stabilised, and which benefits the soil when added to it.