It’s hard to answer that without actually seeing a modern gift economy in action. Luckily, modern gift economies actually do exist. On a small scale, they exist among friends, who might lend each other a vacuum or a cup of flour. There’s even an example of a gift economy on a much larger scale, albeit one that’s not always in operation: The Rainbow Gathering, an annual festival in which about 10,000 people gather for a month in the woods (it rotates among various national forests around the country each year) and agree not to bring any money. Groups of attendees set up “kitchens,” in which they prepare and serve food for thousands of people every day, all for free. Classical economists might guess that people would take advantage of such a system, but, sure enough, everyone is fed, and the people who don’t cook play music, set up trails, teach classes, gather firewood, and perform in plays, among other things.
Just as with most things, there are disadvantages and advantages of bartering. A complication of bartering is determining how trustworthy the person you are trading with is. The other person does not have any proof or certification that they are legitimate, and there is no consumer protection or warranties involved. This means that services and goods you are exchanging may be exchanged for poor or defective items. You would not want to exchange a toy that is almost brand new and in perfect working condition for a toy that is worn and does not work at all would you? It may be a good idea to limit exchanges to family and friends in the beginning because good bartering requires skill and experience. At times, it is easy to think the item you desire is worth more than it actually is and underestimate the value of your own item.
As Orlove noted, barter may occur in commercial economies, usually during periods of monetary crisis. During such a crisis, currency may be in short supply, or highly devalued through hyperinflation. In such cases, money ceases to be the universal medium of exchange or standard of value. Money may be in such short supply that it becomes an item of barter itself rather than the means of exchange. Barter may also occur when people cannot afford to keep money (as when hyperinflation quickly devalues it).
He would have heard of channels and sandbanks, of natural features of the land useful for sea-marks, of villages and tribes and modes of barter and precautions to take: with the instructive tales about native chiefs dyed more or less blue, whose character for greediness, ferocity, or amiability must have been expounded to him with that capacity for vivid language which seems joined naturally to the shadiness of moral character and recklessness of disposition.
In Spain (particularly the Catalonia region) there is a growing number of exchange markets. These barter markets or swap meets work without money. Participants bring things they do not need and exchange them for the unwanted goods of another participant. Swapping among three parties often helps satisfy tastes when trying to get around the rule that money is not allowed.
Men from the visiting group sit quietly while women of the opposite moiety come over and give them cloth, hit them, and invite them to copulate. They take any liberty they choose with the men, amid amusement and applause, while the singing and dancing continue. Women try to undo the men’s loin coverings or touch their penises, and to drag them from the “ring place” for coitus. The men go with their … partners, with a show of reluctance to copulate in the bushes away from the fires which light up the dancers. They may give the women tobacco or beads. When the women return, they give part of this tobacco to their own husbands.
Other countries though do not have the reporting requirement that the U.S. does concerning proceeds from barter transactions, but taxation is handled the same way as a cash transaction. If one barters for a profit, one pays the appropriate tax; if one generates a loss in the transaction, they have a loss. Bartering for business is also taxed accordingly as business income or business expense. Many barter exchanges require that one register as a business.