What is a Byproduct?

A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced.

A by-product can be useful and marketable or it can be considered waste: for example, bran, which is a byproduct of the milling of wheat into refined flour, is sometimes composted or burned for disposal, but in other cases, it can be used as a nutritious ingredient in human food or animal feed. Gasoline was once a byproduct of oil refining that later became a desirable commodity as motor fuel. The plastic used in plastic shopping bags also started as a by-product of oil refining.

What Does Byproduct Mean?

In the context of production, a by-product is the “output from a joint production process that is minor in quantity and/or net realizable value (NRV) when compared with the main products”. Because they are deemed to have no influence on reported financial results, by-products do not receive allocations of joint costs. By-products also, by convention, are not inventoried, but the NRV from by-products is typically recognized as “other income”, or as a reduction of joint production processing costs when the by-product is produced.

The International Energy Agency (IEA) defines by-product in the context of life-cycle assessment by defining four different product types: “main products, co-products (which involve similar revenues to the main product), by-products (which result in smaller revenues), and waste products (which provide little or no revenue).”

Unfortunately not all by-products have the same salability and value as the dairy farmers’ and loggers’ operations. Some by-products are simply waste that can’t be used for anything. Take a nuclear power plant for example. The plant generates electricity using a nuclear process that produces nuclear waste. Not only is this material not salable, it is hazardous to store and dispose of. Companies must build highly specialized facilities to store this material and hire employees who can take caution in handling, transporting, and disposing of it.

Accounting for Byproducts

The typical accounting for any revenues generated from byproducts is to offset them against the cost of goods sold for the primary products that are generated from the manufacturing system. It is also acceptable to record these revenues as miscellaneous revenue. Either approach will result in the same net profit figure. However, recording the sale of byproducts as miscellaneous revenue will result in a minor increase in the amount of reported sales. You do not need to assign any material cost or overhead cost to byproducts; instead, it is easier to assign all production costs to the primary products that are being manufactured.

There are other, more complicated methods available for accounting for the cost of byproducts, such as the sales value at split-off method and the net realizable value method, but they introduce considerable complexity to the accounting process, and so should generally be avoided.

When there are multiple products created from a production process, the byproducts can be discerned by seeing which ones have a minor resale value in comparison to the value of the other products. If there is no clear differentiation between primary products and byproducts, treat them all as primary products.