Every Penny Counts: A Case Study in Increasing Savings Through Coin Deposits from Digital Credit Union

Every Penny Counts: A Case Study in Increasing Savings Through Coin Deposits from Digital Credit Union

Tuesday, September 1, 2020

While the days of making penny rolls may be long over, converting coins into cash is not. Every year Americans trade millions in coins into cash, largely through coin deposit machines. These are often found in grocery stores, banks, and credit unions.

Digital Federal Credit Union (DCU) is the largest credit union headquartered in New England and offers access to these machines. In December 2019, Common Cents Lab partnered with DCU to see if there were ways to turn coin deposits into increased savings.

Our research finds that members are more likely to save a portion of their coin slip when tellers directly ask members if they’d like to save – this has implications for all credit unions, banks and other operators who offer coin exchanges and foster the savings habit.


The coin machines that DCU offers are popular among members. Collected baseline data shows that coin deposit amounts average to $91 with a $45 median. While 3% of members split their slip amounts between cash, savings, and their checking accounts, more than 80% of members either cash the entire amount or deposit it directly into their checking account. Only a handful of members choose to save their coin deposits.

Hypothesis and Key Insights

Our baseline data collection indicated that a large portion of members cashed their coin machine slip, likely in order to spend the money from the coin deposit. This makes sense – spare change is rarely taken into account when creating budgets. Similar to tax refunds, people think of the extra money from spare change as a separate windfall that exists outside of someone’s normal mental accounting. The money can be spent without the same constraints that people place on income from other sources, but that also means coin deposits represent an interesting opportunity to nudge individuals to deposit all or a portion of the coin slip amounts into savings.

We thought that a few small nudges might increase the number of members who saved their coin deposit windfalls. To determine how we might go about developing an intervention, we started by understanding the process in detail and quickly identified a few touch points with members. The machines convert spare change into a slip with the total amount printed on it. Members then take the slip directly to a teller, at which point they must decide whether to cash the slip or deposit the amount into one of their accounts.


Together with DCU, we worked to change the choice architecture around the coin deposit process. The new process included a salient reminder to save, as well as an active choice with an implied default that encouraged members to deposit their coin amounts into a savings account We randomly assigned DCU branches into two conditions.

Business as usual (BAU): In the first set of branches, we posted a behaviorally-designed sign by the coin machines. The sign is intended to be a reminder for members using the machines to consider saving when they may not have previously. Otherwise, teller and member interactions were no different than usual.

New savings script: In the second set of branches, the savings message communicated by the sign was reinforced by tellers. When a member takes their coin machine slip to the teller, the tellers will say,  “Can I go ahead and deposit this into your primary savings account today?” This script intended to imply that saving a portion of the slip was the expected and default behavior.


The study was launched through the month of December 2019. Tellers in both conditions tracked the number of coin machine transactions, and the amounts cashed out, or deposited into checking or savings accounts for four weeks. In total, DCU tellers tracked 3,302 coin machine transactions.

Those in the new savings script group were more likely to agree to save a portion of their coin slip into their DCU primary savings account (23.1% in BAU group, 26.6% in savings script group, p = 0.006). Interestingly, when we look at just those who decided to save, those in the BAU group saved a higher percentage of their coin slip (62% vs. 54%, p = 0.049). So, while the savings script condition appears to have led more people to agree to save, those who agreed to save tended to save a smaller percentage of their slip, on average.

We think that this is because the implied default in the savings script convinced members to at least save a portion, bringing down the average amount saved. Indeed, while an equal number of members in both groups saved their whole slip, members in the savings script group were more likely to save a portion of their slip compared to the BAU group (p = 0.001).

Taken together, we believe that the analysis suggests the new savings script successfully nudged members who otherwise would not have saved at all to save, even if it was just a small portion of their coin slip. Money earned from coins presents itself as a unique windfall opportunity for tellers to encourage small dollar savings by simply just asking members. If scaled, every penny would count, quite literally, towards building savings.

BlackRock’s Emergency Savings Initiative

BlackRock announced a $50 million commitment to help millions of people living on low to moderate incomes gain access to and increase usage of proven savings strategies and tools – ultimately helping them establish an important safety net. The size and scale of the savings problem requires the knowledge and expertise of established industry experts that are recognized leaders in savings research and interventions on an individual and corporate level. Led by its Social Impact team, BlackRock is partnering with innovative industry experts Common Cents Lab, Commonwealth, and the Financial Health Network to give the initiative a comprehensive and multilayered approach to address the savings crisis. UPS, Uber, Mastercard, Etsy, Brightside, Arizona State University, and Acorns have joined BlackRock’s Emergency Savings Initiative to help their employees, customers, gig workers, and college students take the essential first step toward long-term financial well-being.