The cost of debt must be based upon the current market cost of debt. Where different kinds of debt are used estimates of more than one debt cost may be necessary and these costs weighted according to the proportion of each type of debt that is used. The deliverance yield of existing debt may be used to estimate the cost of debt if no obvious market price is available. If the company is in the taxpaying position the cost of debt must be estimated net of any tax relief on interest paid on the debt.