a tax that is levied on documents. Historically, this included the majority of legal documents such as cheques, receipts, military commissions, marriage licences and land transactions. A physical stamp (a revenue stamp) had to be attached to or impressed upon the document to denote that stamp duty had been paid before the document was legally effective. More modern versions of the tax no longer require an actual stamp.
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[In the United States,] this tax, known variously as a mortgage tax, intangibles tax, or documentary stamp tax, is also usually collected at the time of registration of the mortgage or deed of trust with the recording authority.
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Blackadder: We must buy Dunny-on-the-Wold at once and thus control the voter. I shall need a thousand pounds.
George: A thousand pounds? I thought you said it was a tuppenny-ha'penny place.
Blackadder: Well, yes, sir, the land will cost tuppence-ha'penny, but there are many other factors to be considered: stamp duty, window tax, swamp insurance, hen food, dog biscuits, cow ointment -- the expenses are endless.