Selling to excsiable unit by non-excsiable unit

Non excisable units can charge either cst/ vat and excise cannot be passed. Cusotmer cannot claim cenvat. An alternative is that the cusotmer buys the raw material and supplies it to you under job work. Regular pre numbered commercial invoice is sufficiant. 

Suggestion: Since you are a manufacturer supplier to units who can avil the cenvat credit unless your growth prospects are not good, you should voluntarily register under central excise much before you reach the 150 L limit. Assuming that your raw material cost is 60% then you are losing 7% margin as the duty charged by your suppliers is a cost to you. In addition, the central excise duty on your capital goods and inputs services is also being lost. This would help you to add margin to your profit or/ and make you competitive to the extent of about 8% in total.