Yet if windows become more expensive, people will demand fewer of them. People reacted to the window tax by bricking over their windows. Old homes with bricked over windows can still be seen throughout Britain.

The window tax was relatively easy to administer. A person's tax liability could be calculated by counting their windows. It had progressive elements. People with higher incomes had larger houses, and more windows, thus paid more in taxes. Houses with fewer than 10 (later 7) windows were exempt from the tax.

The picture on the left shows a home built in 1592 with bricked over windows on the top floor, and on the right a cartoon depicting people's longing for light. The deadweight loss of the window tax was the reduction in well-being it caused, over and above any loss of income associated with paying the tax - the human costs of living and working in dark rooms with no ventilation. A recent paper by Chantal Stebbings argues that this burden was highest for the urban poor, who typically lived in larger tenement buildings, so did not benefit from the seven window exemption, and were vulnerable to the effects of crowding, poor sanitation and disease. Imagine cooking dinner over a coal fire in an unventilated room, or living with someone with tuberculosis, and being unable to open a window. Even in the dwellings of the wealthy, like Hough End Hall, shown above, the bricked up windows are on the top floor, which was typically the servants' quarters.

The window tax is perhaps the most famous example of a tax with visible impacts on building construction, but it is far from the only one. In 1784 the British introduced a brick tax of 4 shillings per thousand bricks. Builders responded by turning to other types of construction materials; manufacturers responded by making bigger bricks. The picture on the left shows the impact of the tax; the building with the "High St" sign is made with smaller, pre-tax brick work.

Tax minimizing construction choices can be seen in Canada, too. The snow-covered dwelling pictured on the right is Jones House, built in Ottawa in around 1890. The Second Empire Mansard styled roof provides the maximum possible amount of living space on the second floor, while still allowing the house to be taxed as a one and a half storey dwelling.

When it comes to taxation, the devil is in the details, as the saying goes. When property tax assessments are based on a building's physical characteristics - the number of windows, the number of storeys - people will argue about what counts as a window, or what counts as a storey.

Even something like the size of a building must be carefully defined for tax purposes. Are property taxes based on the interior or exterior dimensions of a building, its size at ground level, or its size including any balconies, overhangs, or eaves? The next set of pictures show what is at stake in defining a building's dimensions.



The picture on the left below shows Ottawa's Mayfair Theatre in 1944; the picture on the right shows the same theatre today. In Ottawa taxes are levied any part of a building that overhangs the sidewalk. The Mayfair theatre's marquee was not, in fact, removed for tax reasons, but other marquees were.

Taxes are still influencing building construction today. Egypt taxes finished buildings at one rate; unfinished buildings at another lower, rate. As a result, developers leave their buildings unfinished, typically with a half-built upper story, as shown in the last picture.

The primary purpose of these pictures is to provide a concrete illustration of the efficiency impacts of taxes, to create a more memorable and meaningful image than a deadweight loss triangle.

Yet these pictures also serve as a reminder the strengths of broad-based income and consumption taxes. The re-introduction of income tax in 1842 made the repeal of the much-hated English window tax possible. Value added taxes remove any incentives to minimize tax liabilities by up-sizing bricks. Good tax policy in four words: broad base; low rate.