The ordinary progress of a society which increases in wealth is at all times to augment the incomes of landlords — to give them both a greater amount and a greater proportion of the wealth of the community, independently of any trouble or outlay incurred by themselves. They grow richer as it were in their sleep, without working, risking or economizing. What claims have they, on the general principles of social justice, to this accession of riches?
— JOHN STUART MILL, Principles of Political Economy, Book V., Chap. 2, Sec. 5
§5. Before leaving the subject of Equality of Taxation, I must remark that there are cases in which exceptions may be made to it, consistently with that equal justice which is the groundwork of the rule. Suppose that there is a kind of income which constantly tends to increase, without any exertion or sacrifice on the part of the owners: those owners constituting a class in the community, whom the natural course of things progressively enriches, consistently with complete passiveness on their own part. In such a case it would be no violation of the principles on which private property is grounded, if the state should appropriate this increase of wealth, or part of it, as it arises. This would not properly be taking anything from anybody; it would merely be applying an accession of wealth, created by circumstances, to the benefit of society, instead of allowing it to become an unearned appendage to the riches of a particular class.
Now this is actually the case with rent. The ordinary progress of a society which increases in wealth, is at all times tending to augment the incomes of landlords; to give them both a greater amount and a greater proportion of the wealth of the community, independently of any trouble or outlay incurred by themselves. They grow richer, as it were in their sleep, without working, risking, or economizing. What claim have they, on the general principle of social justice, to this accession of riches? In what would they have been wronged if society had, from the beginning, reserved the right of taxing the spontaneous increase of rent, to the highest amount required by financial exigencies? I admit that it would be unjust to come upon each individual estate, and lay hold of the increase which might be found to have taken place in its rental; because there would be no means of distinguishing in individual cases, between an increase owing solely to the general circumstances of society, and one which was the effect of skill and expenditure on the part of the proprietor. The only admissible mode of proceeding would be by a general measure. The first step should be a valuation of all the land in the country. The present value of all land should be exempt from the tax; but after an interval had elapsed, during which society had increased in population and capital, a rough estimate might be made of the spontaneous increase which had accrued to rent since the valuation was made. Of this the average price of produce would be some criterion: if that had risen, it would be certain that rent had increased, and (as already shown) even in a greater ratio than the rise of price. On this and other data, an approximate estimate might be made, how much value had been added to the land of the country by natural causes; and in laying on a general land-tax, which for fear of miscalculation should be considerably within the amount thus indicated, there would be an assurance of not touching any increase of income which might be the result of capital expended or industry exerted by the proprietor.
But though there could be no question as to the justice of taxing the increase of rent, if society had avowedly reserved the right, has not society waived that right by not exercising it? In England, for example, have not all who bought land for the last century or more, given value not only for the existing income, but for the prospects of increase, under an implied assurance of being only taxed in the same proportion with other incomes? This objection, in so far as valid, has a different degree of validity in different countries; depending on the degree of desuetude into which society has allowed a right to fall, which, as no one can doubt, it once fully possessed. In most countries of Europe, the right to take by taxation, as exigency might require, an indefinite portion of the rent of land, has never been allowed to slumber. In several parts of the Continent, the land-tax forms a large proportion of the public revenues, and has always been confessedly liable to be raised or lowered without reference to other taxes. In these countries no one can pretend to have become the owner of land on the faith of never being called upon to pay an increased land-tax. In England the land-tax has not varied since the early part of the last century. The last act of the legislature in relation to its amount, was to diminish it; and though the subsequent increase in the rental of the country has been immense, not only from agriculture, but from the growth of towns and the increase of buildings, the ascendancy of landholders in the legislature has prevented any tax from being imposed, as it so justly might, upon the very large portion of this increase which was unearned, and, as it were, accidental. For the expectations thus raised, it appears to me that an amply sufficient allowance is made, if the whole increase of income which has accrued during this long period from a mere natural law, without exertion or sacrifice, is held sacred from any peculiar taxation. From the present date, or any subsequent time at which the legislature may think fit to assert the principle, I see no objection to declaring that the future increment of rent should be liable to special taxation; in doing which all injustice to the landlords would be obviated, if the present market-price of their land were secured to them; since that includes the present value of all future expectations. With reference to such a tax, perhaps a safer criterion than either a rise of rents or a rise of the price of corn, would be a general rise in the price of land. It would be easy to keep the tax within the amount which would reduce the market value of land below the original valuation: and up to that point, whatever the amount of the tax might be, no injustice would be done to the proprietors.*28