Of American-English origin, the phrase to go Dutch means to have every participant pay for his or her own expenses, also to share expenses equally.
I have discovered that to go Dutch is in fact a shortening of to go Dutch treat, which itself arose from the noun Dutch treat, also of American-English origin, denoting a meal, outing, entertainment, at which each participant pays for his or her share of the expenses.
The earliest occurrences of Dutch treat that I have found date from June 1873; the origin of this noun was explained in an article titled Beer, Letter from Vienna to the Baltimore American, published on Friday 20th in The Chicago Daily Tribune (Chicago, Illinois)—this article shows that in Dutch treat, the adjective Dutch is used in the sense of German [cf. origin of ‘double Dutch’ and ‘High Dutch’ (‘gibberish’) and footnote 1]:
The Germans in the United States, and those Americans who affect a fondness for lager-beer, don’t drink it as it is drank in Germany. They rush into a restaurant and gulp down two or three glasses and move on. Here a German never thinks of finishing his glass of beer in less than ten minutes, and to drink it without eating something at the same time, even if it is only a crust of brown bread. In fact, a German in the Fatherland is constitutionally opposed to doing anything in a hurry, and especially to drinking beer with “rapid speed.” The consequence is that we do not see men here with great, huge paunches, as at home, capable of swallowing a keg of beer after supper. They seldom treat one another, but sit down to the tables, and although they drink together, each man pays for what he consumes, whether it be beer or food. This of itself is a great preventive of excess, as, if half a dozen or a dozen were to sit down to drink, as with us, each must treat in turn, and thus six or a dozen glasses to be guzzled, whether they want it or not. If our temperance friends could institute what is called the “Dutch treat” into our saloons, each man paying his own reckoning, it would be a long step toward reform in drinking to excess. In short, beer in Germany is a part of each man’s food. He takes it as a sustenance, and not as a stimulant.
(In Dutch treat, therefore, the adjective Dutch is not used in the derogatory manner in which it is used in Dutch courage, nor does it refer specifically to the Netherlands, as it does in Dutch auction.)
The noun Dutch treat gave rise to the phrase to go Dutch treat. The earliest occurrence that I have found is from the column The Talk of New York, in The Brooklyn Daily Eagle (Brooklyn, New York) of Sunday 13th November 1887:
There’s a curious feature developing itself here among the female theater goers—their independence of the other sex. […] There is a great deal of this sort of thing at the opera, too, particularly in the upper galleries. Poor, music loving girls often haven’t any wealthy male relatives or friends to take them and are able on a pinch to pay for their own seats and no more. Some friend of theirs is in the same fix and they go “Dutch treat” and are never annoyed in any way, though they make the journey back and forth in the horse cars.
The earliest instance of the shortened phrase to go Dutch, used in its current sense [see footnote 2], that I have found is from Does Office Chumming Pay?, by Anna S. Richardson, published in the magazine supplement, “A Section Devoted Entirely to Women’s Interests”, of The Inter Ocean (Chicago, Illinois) of Sunday 2nd June 1907:
[The chummy girl] wants to be with the men all the time. When they do not invite her to lunch individually she is quite willing to go “Dutch”—that is, paying her share of the check and sitting at the same table with three or four of the boys.
illustration for Does Office Chumming Pay?
The Inter Ocean (Chicago, Illinois) – Sunday 2nd June 1907
In Germany, the adjective was used (in the 9th century) as a rendering of Latin ‘vulgaris’, to distinguish the ‘vulgar tongue’ from the Latin of the church and the learned; hence it gradually came to be the current denomination of the vernacular, applicable alike to any particular dialect, and generically to German as a whole. From the language, it was naturally extended to those who spoke it (compare ‘English’), and thus grew to be an ethnic or national adjective; whence also, in the 12th or 13th century, arose the name of the country, ‘Diutisklant’, now ‘Deutschland’, = ‘Germany’.
In the 15th and 16th centuries, ‘Dutch’ was used in England in the general sense in which we now use ‘German’, and in this sense it included the language and people of the Netherlands as part of the ‘Low Dutch’ or Low German domain. After the United Provinces became an independent state, using the ‘Nederduytsch’ or Low German of Holland as the national language, the term ‘Dutch’ was gradually restricted in England to the Netherlanders, as being the particular division of the ‘Dutch’ or Germans with whom the English came in contact in the 17th century; while in Holland itself ‘duitsch’, and in Germany ‘deutsch’, are, in their ordinary use, restricted to the language and dialects of the German Empire and of adjacent regions, exclusive of the Netherlands and Friesland; though in a wider sense ‘deutsch’ includes these also, and may even be used as widely as ‘Germanic’ or ‘Teutonic’. Thus the English use of ‘Dutch’ has diverged from the German and Netherlandish use since 1600.
The following passage from The Origin of the English Nation, by Edward A. Freeman, published in Macmillan’s Magazine (London) in March 1870, shows how Dutch has long been used “in the general sense in which we now use German”, including the language of the Netherlands as part of the Low-Dutch, i.e. Low-German, domain:
We may […] divide the Teutonic languages into two classes, the High-Dutch and the Low. The former is the tongue of Southern or Upper Germany, the high lands away from the sea and near the sources of the rivers. The latter is the tongue of Northern, Lower, or Nether Germany, the lands near the sea and at the mouths of the rivers, the speech of what we specially call the Netherlands or Low Countries, and of the great plain stretching away eastward till we get out of the reach of Teutonic and Aryan languages altogether.
2-: I have found an earlier instance of to go Dutch, used in a different sense, in an interview of Frank Carr, “one of St. Louis’ well-known bookmakers”, published in the St. Louis Post-Dispatch (St. Louis, Missouri) of Sunday 22nd March 1903:
“It used to be that the bookmakers all did the business with their own money, but today it is different. […]
“When a man is conducting a business on somebody’s else money, he will take greater risks than the man who stands to lose his own money.
“For this reason, the books of today are run on a great deal smaller percentage than they used to be, and some of them will even go ‘Dutch’ to get the money. What I mean by going ‘Dutch,’ is to do business on less than an even percentage.”