Pest control campaigns

• The Great Hanoi Rat Massacre occurred in 1902, in Hanoi, Vietnam (then known as French Indochina), when, under French colonial rule, the colonial government created a bounty program that paid a reward for each rat killed.^[3] To collect the bounty, people would need to provide the severed tail of a rat. Colonial officials, however, began noticing rats in Hanoi with no tails. The Vietnamese rat catchers would capture rats, sever their tails, then release them back into the sewers so that they could produce more rats.^[6]
• Experiencing an issue with feral pigs, the U.S. Army post of Fort Benning (now named Fort Moore) in Georgia offered hunters a $40-bounty for every pig tail turned in.^[7] Over the course of the 2007–2008 program, the feral pig population in the area increased. While there were some reports that individuals purchased pigs' tails from meat processors^[8] then resold the tails to the Army at the higher bounty price, a detailed study of the bounty scheme found different effects from perverse incentives were mainly responsible. Both the pigs' fertility rate and offspring survival rates increased under the scheme. This was due to improved nutrition made available by the feed bait used to attract the animals to hunting sites. Secondly, hunters were found to be more likely to preferentially target large males as "trophy"-quality game, while ignoring females and juveniles as targets. Removal of mature males from the population has a negligible impact on population growth, as remaining mature males can each stud many breeding sows.^[9]

Community safety and harm reduction

• In 2002 British officials in Afghanistan offered Afghan poppy farmers $700 an acre in return for destroying their poppy crops. This ignited a poppy-growing frenzy among Afghan farmers who sought to plant as many poppies as they could in order to collect payouts from the cash-for-poppies program. Some farmers harvested the sap before destroying the plants, getting paid twice for the same crop.^[10]
• Gun buyback programs are carried out by governments to reduce the number of guns in circulation, by purchasing firearms from citizens at a flat rate (and then destroying them). Some residents of areas with gun buyback programs have 3D printed large numbers of crude parts that met the minimum legal definition of a firearm, for the purpose of immediately turning them in for the cash payout.^[11][12]
• The FASTER Act of 2021 in the U.S. was intended to aid those with an allergy to sesame in avoiding the substance by ensuring foods that contain it are labeled. However, the stringent requirements for preventing cross-contamination if the ingredients did not include sesame made it simpler and less expensive for many companies to instead add sesame to their products and label it as an ingredient, decreasing the number of sesame-free products available and creating the risk of an allergic reaction occurring from previously safe foods.^[13]

Environmental and wildlife protection

• The United States Endangered Species Act of 1973 imposes development restrictions on landowners who find endangered species on their property.^[14] While this policy has some positive effects for wildlife, it also encourages preemptive habitat destruction (draining swamps or cutting down trees that might host valuable species) by landowners who fear losing the lucrative development-friendliness of their land because of the presence of an endangered species.^[15] In some cases, endangered species may even be deliberately killed to avoid discovery.^[14] This same perverse incentive has also been observed in other countries, including Canada and various European countries.
• In 2005 the UN Intergovernmental Panel on Climate Change began an incentive scheme to cut down on greenhouse gases. Companies disposing of polluting gases were rewarded with carbon credits, which could eventually get converted into cash. The program set prices according to how serious the damage the pollutant could do to the environment was and attributed one of the highest bounties for destroying HFC-23, a byproduct of a common coolant, HCFC-22. As a result, companies began to produce more of this coolant in order to destroy more of the byproduct waste gas, and collect millions of dollars in credits.^[16] This increased production also caused the price of the refrigerant to decrease significantly, motivating refrigeration companies to continue using it, despite the adverse environmental effects.^[17][18] In 2013, credits for the destruction of HFC-23 were suspended in the European Union.^[19]
• Renewable Heat Incentive scandal – (commonly referred to as the Cash for Ash scandal) Introduced by the devolved government in Northern Ireland, the Renewable Heat Incentive (RHI) was a 20-year scheme intended to encourage businesses to reduce energy usage and promote switching to green sources. However, the subsidy for the renewable energy was greater than its cost, which allowed businesses to make a profit by switching to green sources and then increasing their energy use rather than reducing it. In some cases, an income was obtained simply by heating empty buildings. The political fall-out caused the Northern Ireland Executive to collapse in 2017. It was not re-convened until 2020.^[20][21]

Historic preservation schemes

As an incentive to preserve historical buildings, governments may designate older structures as historical properties; such classification may prevent or impede further sale or alteration of the property. Any compensation offered may be significantly less than normal commercial returns on properties or land. Examples related to this type of perverse incentive include:

• The United Kingdom's listed building regulations are intended to protect historically important buildings by requiring owners to seek permission before making changes to buildings that have been listed. In 2017, the owners of an unlisted historic building in Bristol destroyed a 400-year-old ceiling the day before a scheduled visit by listings officers, allegedly to prevent the building from being listed, which could have limited future development.^[22][23]
• According to the National Trust for Historic Preservation an increase in arson in the United States in the 1970s may have been the result of perverse incentives arising from government regulation: In particular, the Tax Reform Act of 1976 provided for loss of tax benefits if owners demolished buildings, possibly promoting arson as a way of clearing land without financial penalty. The law was later altered to remove this aspect.^[24]

Healthcare cost control

• Paying medical professionals and reimbursing insured patients for treatment but not prevention encourages medical conditions to be ignored until treatment is required.^[25] Moreover, paying only for treatment effectively discourages prevention (which would improve quality of life for the patient but would also reduce the demand for future treatments). Payment for treatment also generates a perverse incentive for unnecessary treatments that could be harmful – for example, in the form of side effects of drugs and surgery. These side effects themselves can then trigger a demand for further treatments.
• Under the American Medicare program, doctors are reimbursed at a higher rate if they administer more expensive medications to treat a condition. This creates an incentive for the physician to prescribe a more expensive drug when a less expensive one might do.^[26]

Humanitarian and welfare policies

• In the 2000s, Canada negotiated a "Safe Third Country Agreement" with the U.S. under which applicants for political asylum could only apply in the first of the two countries they reached, in order to discourage asylum shopping. Among the provisions was one that denied anyone entering Canada at an official port of entry from requesting asylum there, in theory limiting asylum applications to either those filed by refugees in camps abroad or those who could legally travel to Canada and do so at an immigration office. In the late 2010s, some migrants began entering Canada irregularly, between official border crossings, at places like Roxham Road between New York and Quebec, since once they were in Canada, they were allowed to file applications with the full range of appeals available to them, a process that could take years. Canada wound up processing thousands more applications for asylum than it had planned to.^[27]
• The "welfare trap" theory describes perverse incentives that occur when money earned through part-time or minimum-wage employment results in a reduction in state benefits that would have been greater than the amount earned, thereby creating a barrier to low-income workers re-entering the workforce.^[28] According to this theory, underlying factors include a full tax exemption for public assistance while employment income is taxed; a pattern of welfare paying more per dependent child (while employers are prohibited from discriminating in this manner, and their workers often must purchase daycare); or loss of welfare eligibility for the working poor ending other means-tested benefits (public medical, dental, or prescription drug plans; subsidised housing; legal aid), which are expensive to replace at full market rates. If the withdrawal of means-tested benefits that comes with entering low-paid work causes there to be no significant increase in total income or even a net loss, then this gives a powerful disincentive to take on such work.^[29]

Promotional schemes and public relations

• Hacktoberfest is an October-long celebration to promote contributions to the free and open-source software communities. In 2020, participants were encouraged to submit four or more pull requests to any public free or open-source (FOS) repository, with a free "Hacktoberfest 2020" T-shirt for the first 75,000 participants to do so.^[30] The free T-shirts caused thousands of frivolous pull requests on FOS projects.^[31]
• Around 2010, online retailer Vitaly Borker found that customer posts elsewhere on the Internet about negative experiences with his eyeglass-sale website, DecorMyEyes, actually drove more traffic to it since the sheer volume of links pushed the site to the top of Google searches. He thus made a point of responding to customer complaints about the poor quality of the merchandise they received and/or misfilled orders rudely, with insults, threats of violence and other harassment.^[32] Borker continued these practices under different names throughout the next decade despite serving two separate sentences in U.S. federal prison over charges arising from them.^[33]

Returns for effort

• The 20th-century paleontologist G. H. R. von Koenigswald used to pay Javanese locals for each fragment of hominin skull that they produced. He later discovered that the people had been breaking up whole skulls into smaller pieces to maximize their payments.^[34]
• In building the first transcontinental railroad in the 1860s, the United States Congress agreed to pay the builders per mile of track laid. As a result, Thomas C. Durant of Union Pacific Railroad lengthened a section of the route, forming a bow shape and unnecessarily adding miles of track.^[35]
• Funding fire departments by the number of fire calls that are made is intended to reward fire departments that do the most work. However, it may discourage them from fire-prevention activities, leading to an increase in actual fires.^[36]