The sales-value-at-split-off method can be approximated through the use of weighting factors based on price. The advantage is that the price-based weights do not change as market prices do. An example of this method is found in the glue industry. Material is put into process in the Cooking Department. The products resulting from the cooking operations are the several "runs of glue."The first run is of the highest grade, has the highest market value, and costs the least. Successive runs require higher temperatures, cost more, and produce lower grades of products. Glue factories do not attemp to determine the actual cost of each skimming because the effect would be to show the lowest cost on the first grade of product and the highest cost on the lowest grade. Instead, the cost of all glue produced is determined, and this total cost is spread over the various grades on the basis of their respective tests of purity. The relative degree of purity is an indicator of the quality and, therfore, of the market value of each run or grade produced. Hence, multiplying the yield for each run by its relative purity is equivalent to multiplying it by the market value. The amounts weighted by purity are used to allocate the joint costs to each run. Additional runs would be undertaken, of course, only as long as the incremental costs incurred.
The weighting factor based on market value at split-off is conceptually the same as the weighting factor method under physical units. However, in the case, the weighting factor is based on sales value, while the weighting factor described in the physical units section could be based on other considerations such as processing difficulty, size, and so on that may or may not be related to market value.
Net Realizable Value Method
When market value is used to allocate joint costs, we are talking about market value at the split-off point. However, on occasion, there is no ready market price for the individual products at the split-off point. In this case, the net realizable value method can be used. First, we obtain a hypothetical sales value for each joint product by subtracting all separable (or further) processing costs from the eventual market value. This approximates the sales value at split-off. Then, The net realizable value method can be used to prorate the joint costs based on each products's share of hypothetical sales value. Cornerstone7.10 shows how and why to use the net realizable value method to allocate joint costs.
The net realizable value method is particularly useful when one or more products cannot be sold at the split-off point but must be processed further.