If I am depreciating equipment using the straight line method, how do I calculate these amounts.

Equipment own that cost $50,000 purchased Jan 1, 2008 with an estimated salvage value of $5000 and useful life of 5 years.
May 1 2011 sold for $28,000
Oct 1 2011 sold for $11,000

I know I have to find the depreciation for one year which is $9000 (50000-5000=45000/5) For one year $9000 two year $18000 and so on until I reach 45000. For one month the equipment is depreciated at $750 but with this being May and October I am confused.

straight line depreciation with a five year life. How much of the five years (60 months) was used? Not sure about your estimated salvage value. I'm a small business owner, not an accountant, which is why I have an accountant. Yea it sucks paying someone to tell you how much to pay for taxes! But it really sucks when you pay too much because you don't know how to figure out the thousands of rules. $50,000 object for 60 months, looses about $833 each month. Multiply that by the number of months before it was sold and subtract that from the acquisition cost gives you the depreciated value. Now what do you pay in taxes? Why did you sell it? Time to ask your friends about a good accountant. Disclosure: I am not and never have been an accountant, and have no financial interests with any accountant or firm (but I have a cousin who is a CPA with a public utility).

First you have to get the depreciation amount for each year.

So take your cost minus your salvage value to get your depreciable base. Next take your depreciable base and divide it by number of years useful life to get your depreciation per year.

Now for the partial year take the depreciation per year times number of months used divided by 12 months.

So for May 1, 2011 you have depreciation for full years in 2008, 2009, and 2010, which is 3 years and from Jan 1 to May 1 in 2011, which is 5 months so just add 3 months of depreciation, calculate 5 months of depreciation and add the amounts together.

For Oct 1, 2011 you will have depreciation for 2008, 2009, and 2010 or 3 full years and from Jan 1 to Oct 1 in 2011, which is 9 months. So calculate 3 full years of depreciation and 9 months of depreciation and then just add the amounts together.