Read a radical proposal a couple months ago, actually from two different sources at opposite ends of the political left/right scale, and both came to a single interesting conclusion:
The best tax reform would be to eliminate income taxes entirely (on individuals and corporations) and implement goods/services taxes on all consumables at flat percentage rates, and targeted to industry (e.g. a general consumption/service tax, fuel taxes, electronics recycling taxes, etc). This accomplishes several basic objectives:
1. All persons pay taxes equally according to their consumption, as opposed to disproportionately based on their wealth (and ability to dodge taxes, since we all know that a large proportion of wealthy persons and corporations pay no taxes in the current system). Buy a bigger plane, you pay more for it. Businesses are equally subject to such a tax which eliminates the need for corporate income taxation.
2. Eliminates taxation loopholes and ensures automatic collection. If taxes are owed based on consumption, they are collected by the seller and required to be forwarded to the taxing authority. This prevents people from dodging their taxes, and audits would ensure corporate record-keeping was accurate and the correct amounts were forwarded. No more tax havens for the wealthy - and no more "business write-offs."
3. Consumption-based taxation gives incentive for people to reduce usage and increase self-sufficiency.
4. For low-income earners who are typically the hardest hit, a tax rebate could be issued quarterly to those below a set income threshold in percentage increments. This is already done for federal taxes in Canada. This ensures that the poor are not disproportionately affected on consumption of essential goods.
I strongly favour this type of taxation format because it is fair and difficult to avoid, and because it targets human behaviour. Right now if you want to reduce your tax burden you have a variety of options which always involve either earning less, OR dabbling in financial instruments that allow for deferred taxes or relieved taxes if you have the necessary disposable income to do so, which eliminates all of the lower classes and much of the middle class. Only the top earners benefit from the current taxation scheme used in most of the G8.
Also, corporate taxes are so full of loopholes that they are ridiculous - large corporations pay no tax, while small entrepreneurs pay their full amount, which is why high corporate taxes are universally bad - they stifle grow. Taxation should be aimed at people and entities which accumulate and consolidate wealth, not those which cause quantifiable gains in wealth through job creation and innovation.