Generally, if you engaged in a trade or business in which the production, purchase, or sale of merchandise was an income-producing factor, you must take inventories into account at the beginning and end of your tax year.taxmap/instr/i1040sc-010.htm#TXMP45ae09b0
If you are a qualifying taxpayer or a qualifying small business taxpayer (discussed next), you can account for inventoriable items in the same manner as materials and supplies that are not incidental. Under this accounting method, inventory costs for raw materials purchased for use in producing finished goods and merchandise purchased for resale are deductible in the year the finished goods or merchandise are sold (but not before the year you paid for the raw materials or merchandise, if you are also using the cash method). Enter amounts paid for all raw materials and merchandise during 2009 on line 36. The amount you can deduct for 2009 is figured on line 42.taxmap/instr/i1040sc-010.htm#TXMP524b24f8
This is a taxpayer (a) whose average annual gross receipts for the 3 prior tax years are $1 million or less, and (b) whose business is not a tax shelter (as defined in section 448(d)(3)).taxmap/instr/i1040sc-010.htm#TXMP6edf25cc
This is a taxpayer (a) whose average annual gross receipts for the 3 prior tax years are $10 million or less, (b) whose business is not a tax shelter (as defined in section 448(d)(3)), and (c) whose principal business activity is not an ineligible activity as explained in Rev. Proc. 2002-28. You can find Rev. Proc. 2002-28 on page 815 of Internal Revenue Bulletin 2002-18 at www.irs.gov/pub/irs-irbs/irb02-18.pdf
File Form 3115 if you are a qualifying taxpayer or qualifying small business taxpayer and want to change to the cash method or to account for inventoriable items as non-incidental materials and supplies.taxmap/instr/i1040sc-010.htm#TXMP557575fc
For additional guidance on this method of accounting for inventoriable items, see the following.
Certain direct and indirect expenses may have to be capitalized or included in inventory. See the instructions for Part II on page C-4. See Pub. 538 for additional information.
Your inventories can be valued at cost; the lower of cost or market; or any other method approved by the IRS. However, you are required to use cost if you are using the cash method of accounting.taxmap/instr/i1040sc-010.htm#TXMP64a48e8e
If you are changing your method of accounting beginning with 2009, refigure last year's closing inventory using your new method of accounting and enter the result on line 35. If there is a difference between last year's closing inventory and the refigured amount, attach an explanation and take it into account when figuring your section 481(a) adjustment. For details, see the example on page C-3 under Line F.taxmap/instr/i1040sc-010.htm#TXMP3240ef97
If you account for inventoriable items in the same manner as materials and supplies that are not incidental, enter on line 41 the portion of your raw materials and merchandise purchased for resale that is included on line 40 and was not sold during the year.