The costs of manufacturing joint products before the split off are called joint costs and they are not relevant in further decision making?

This statement is not entirely accurate. Joint costs are indeed incurred before the split-off point when multiple products are produced simultaneously from a common input. However, joint costs are relevant in further decision-making because they need to be allocated to the individual products in order to determine their profitability and make pricing decisions.

In addition, joint costs can also be relevant in decisions regarding whether to continue producing a particular product or discontinue it, as well as in determining the optimal production levels for each product. Therefore, it is important to consider joint costs in decision-making processes related to joint products.

False