When accounting for joint products, I typically use one of two methods: the sales value at split-off method or the relative sales value method. The sales value at split-off method allocates joint costs based on the sales value of each product at the point where they are separated, while the relative sales value method allocates joint costs based on the estimated sales value of each product after further processing.
For byproducts, I usually credit the net realizable value (sales value minus any additional processing costs) of the byproduct to the cost of the main product. This helps to reduce the cost of the main product and more accurately reflect its production cost.
I recall a project where I was responsible for accounting for joint products and byproducts in a chemical manufacturing process. By accurately allocating joint costs and crediting the value of byproducts, we were able to provide more accurate cost information for management decision-making.