currently, depreciation is computed per IRC sec 168 using one of these MACRS methods:
• The 200% declining balance method over a GDS recovery period. however, there is a convention that must be applied see below
• The 150% declining balance method over a GDS recovery period.
• The straight line method over a GDS recovery period.
• The straight line method over an ADS recovery period
Turbo-tax is correct. with MACRS depreciation unless 40% or more of property, excluding real estate, is placed in service during the last quarter of the tax year the half-year convention applies. this means for 5-year assets the first year would be 20% (1/2 of 40%) for 5 year property unless you choose one of the other methods
then under MACRS 200 % DB method
year 2 - 32%
year 3 - 19.2%
year 4 and 5- 11.52%
year 6 5.76%
for more information see IRS pub 946
https://www.irs.gov/pub/irs-pdf/p946.pdf
