Rates are set by fiscal year, effective October 1 each year. Find current rates in the continental United States ("CONUS Rates").
Reporting income for a retail business is a bit more involved than for a service business.
For a service business, you simply determine gross receipts then subtract business expenses from gross receipts to arrive at net income.
However, since a retail business carries inventory, an additional element of complexity is added that a service business does not have to deal with.
A retail business purchases items for resale. To make a profit, the cost of all items purchased must be marked up to arrive at a selling price. The selling price of all items sold for the year must be sufficient enough to cover costs and produce a profit.
For example, if unit A is purchased for $10 and marked up 50%, the selling price would be $15 $10 plus (50% x $10). When unit A is sold for the $15, the $15 is called Gross Sales. Of the $15, $10 represents the cost of goods sold.
Beginning inventory cost should match the ending inventory cost of the prior year. If your business is less than one year old, then your beginning inventory is zero.
This is the beginning inventory plus net purchases for the year.
Ending inventory:
This is generally determined by taking a physical count of goods on hand at the end of the year. Each item on hand is assigned a value in order to determine the dollar amount of the inventory on hand. Various cost methods are used to assign a value units of inventory, such as FIFO, LIFO and Average Cost.