Capital Gains v Real Estate tax

I can see several issues with Gareth's proposed tax on real property: accurate assessment of the value of the property- who decides?; accruing a tax burden even when economic conditions prevent having liquid cash to pay on any given year; how to handle a deflated housing market with value actually decreasing. Instead, a fairer regime would be a capital gains tax- pay a tax on the realised gain of property (or stocks or art work) when sold. You have the money for the tax, you know before hand what that will be, and a capital loss (or no gain) doesn't attract any tax burden. Maybe even give a credit for capital loss to offset future gains elsewhere? Fair is fair.