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.
However, if your average annual gross receipts for the 3 prior tax years are $1 million or less and you are an eligible taxpayer who adopts or changes to the cash method of accounting, you will not be required to account for inventories.
If your business has been in existence for less than three years, average gross receipts are determined over the tax years it has been in existence (including annualized amounts for short years). For this purpose, gross receipts are defined as all amounts from the trade or business required to be recognized under your current method of accounting. These amounts include total sales (net of returns and allowances), all amounts received from services, interest, dividends, and rents. You do not have to include taxes that are legally imposed on the purchaser and are merely collected and remitted on their behalf.
If you are not required to account for inventories and do not want to do so, you must treat inventory in the same manner as cost of materials and supplies that are not incidental. Under this rule, inventory costs for raw materials purchased for resale are deductible in the year the finished goods or merchandise are sold (or, if later, the year you paid for the raw materials or merchandise).
If you want to change to the cash method of accounting, you must file Form 3115, Application for Change in Accounting Method. You may also have to make an adjustment to prevent the amounts of income or expense from being duplicated or omitted. This is called a section 481(a) adjustment, which is taken into account over a period not to exceed 4 years.

There are a few choices in terms of bookkeeping software available to a small business owner. The two dominant software packages in the small business market are QuickBooks and Peachtree. A small business owner must consider ease of use, price and support as a software package is chosen assuming that the software will support the business model. The important thing for a small business owner to keep in mind is that although they can input data into a software system it does not mean that financial statements will be usable in terms of accuracy, timeliness and completeness. If you are not an accountant, please keep in mind that a software package will simply be a nice way to be organized and nothing more. A professional will still be needed to prepare complete and accurate financial statements. Timeliness of the financial statements often depends on you and how quickly the documentation and data needed to prepare financial statements are made ready to the accountant by you.