Tie your money to your commitment — but first ask if you’re willing to pay

Cost: Under this deposit‑based approach, participants must put up their own cash upfront; if they fail to meet the target, the money is forfeited. In this trial, the required deposit was $150.
In plain terms: A randomized trial involving 2,538 participants compared two incentive models: one offering a cash reward for success, and another requiring an upfront deposit that is refunded plus a bonus only if the goal is met. Among those willing to join either program, the deposit model produced a success rate 13 percentage points higher than the reward model. Yet only 13.7% of participants agreed to pay the deposit, while 90% opted for the reward option. Thus the deposit approach works best for those willing to pay; for everyone else it essentially has no effect.
Benefit: In a U.S. trial with 2,538 participants, employees and their relatives were randomly assigned to one of four incentive schemes or standard care. The reward model (earning roughly $800 for success) attracted 90.0% participation, whereas the deposit model (requiring a $150 upfront payment plus a $650 bonus) attracted just 13.7%. After six months, overall quit rates ranged from 9.4% to 16.0% across all incentive groups, compared with 6.0% under standard care. The reward model yielded a 15.7% quit rate, while the deposit model produced 10.2%. However, when looking only at the 13.7% of participants willing to pay the deposit, the deposit model achieved a six‑month quit rate 13.2 percentage points higher than the reward model (95% CI 3.1–22.8, a reliable range).
Evidence grade: A
Sources:Halpern SD, French B, Small DS, et al. (2015). Randomized trial of four financial-incentive programs for smoking cessation. New England Journal of Medicine, 372(22), 2108–2117. https://doi.org/10.1056/NEJMoa1414293
Notes: This trial focused on smoking cessation; extrapolating the findings to activities such as essay writing or exercise suggests a moderate overall benefit. The key takeaway is not which method is more effective, but whether you’d actually be willing to use it: a powerful incentive that most people reject is essentially useless for them. Therefore, pick an approach you’re comfortable with — even a modest deposit can be more effective than no deposit at all. For practical smoking‑cessation strategies, see Section 2, Item 3 (smoking‑cessation medications).