Interest on federal savings bonds is taxable; the portion of the redemption representing principal (your initial cost for the bond) is not.
If bonds (Series EE and I) are issued after 1989 and redeemed to pay qualified higher education costs for a taxpayer, spouse, or dependent (and some other conditions are met), some or all of the interest may be tax free, depending on the taxpayer’s overall income. Form 8815 has the details.
Depreciation methods that allow faster write-offs than straight-line rates in the earlier periods of the useful life of an asset. For example, in the first few years of recovery, MACRS allows a 200% double declining balance write-off, twice the straight-line rate.