After some online searching and some analyzing of my own taxes (corporate and personal), I've found that there is a standard timeframe and formula when figuring depreciation for business equipment.
If we're talking non-agricultural, which we are, then the standard for
business equipment is 7 years.
Other depreciation standards for comparison:
Vehicles are 5 years
Office equipment is allowed 5 years
Office furniture & fixtures is 7 years
Residential rental property is 27.5 years
The way to calculate your annual depreciation is to first figure the value of your equipment, place it in the proper expense category, then figure what it's salvage value will be after the standard time frame, subtract that from the value, then divide the difference by the allotted number of years. This is the more common procedure.
E.g. :
Current value of equipment: $10K
Category is 7 year property
Salvage value after 7 years (estimate depending on your variables) is 2K
10K - 2K = 8K
8K divided by 7 years = $1,143.86 annual depreciation
Maintenance and repairs can be fully deducted as business expenses for the year they were incurred. But that's not a depreciation issue.
My accountant doesn't use the salvage value. There's something about using the full purchase price and allowing it to fully expire after 7 years. If I sell my equipment or business however, I will incur the tax liability on the selling price. If you already figured in the salvage value, then your tax liability on the sale expires after the 7 year mark.
These are a few online resources I used for the above info:
http://taxguide.completetax.com/text/c60s15d595.asp
http://en.wikipedia.org/wiki/Depreciation
http://www.nolo.com/article.cfm/cat.../03E7A8D4-EB53-4711-97F91991D9A8468B/213/ART/