It was a tax on farmland, assessed at a fixed annual rate per çift, and paid by land-owning Muslims.
[1] The tax was collected annually, on 1 March, from the holder of the timar or their tax-farmer.
[2] The Çift is a measure of land area, derived from the word for "pair"; it is an area of farmland which can be ploughed by a pair of oxen - the equivalent of the Byzantine Zeugarion.
[4] In the 15th and 16th centuries, most taxpayers in the Ottoman empire paid resm-i çift at a rate somewhere between 22 and 70 akçe; this could have been collected by a sipahi, as either a tax in kind or a cash tax.
However, later centralised tax reforms led to cash payments of avâriz and nüzül replacing resm-i çift; this transition had begun by 1640.