Increasing contributions in automatically enrolled federal employees Year 2018 

What was the goal? 

We wanted to encourage participants who made no changes after being automatically enrolled at 3% of 

salary to increase their contributions. Since eligible participants receive matching on the first 5% of salary, 

saving more would provide interested employees with additional matching from their agencies. 

Who were the participants? 

We contacted 1,254 employees who had been with the federal government for less than two years. All 

employees were automatically enrolled into the TSP between January 1, 2017, and July 1, 2018, and had 

made no changes to the default contribution amount of 3% of salary. All participants worked at agencies 

that used the National Finance Center for payroll transactions, had at least one email address on file, and 

had no outstanding TSP loans. 

How did the project work? 

Participants were randomly assigned into three groups: 

 30% received an email that included vivid colors and design as well as a personalized estimate of 

how much they had missed in matching. 

 30% received an email that featured an estimate of what other people contributing 3% of salary 

had missed. 

 The final 40% received neither email at that time. 

When did this project happen? 

Emails went out in late August 2018, followed by reminders in mid-September 2018. In mid-December 

2018, we noted the total in each group who had started contributing more than 3%, using both Chi square 

and two-sample proportion tests (two-tailed) to determine statistical significance. 

What were the results? 

After 31⁄2 months, 22.7% of those who received the personalized email had increased their contributions 

as did more than a quarter (26.3%) of those who received the email with what others missed. In both 

cases, this was more than double the rate of those who received no email (10.0%) and highly statistically 

significant at the p < 0.0001 level. Both approaches were better than no email, and the difference 

between the personalized approach and what others missed was not statistically significant. 

 
Preventing early max-outs in high-contributors Year 2018 

What was the goal? 

Each year, the IRS limits the amount that participants can contribute to 401(k)-type plans including the 

TSP. For most participants in 2018, that limit was $18,500 (the elective deferral limit). If participants reach 

the limit early, they are not able to contribute their own money to the TSP for the remainder of the 

calendar year. When that happens, eligible participants can miss out on matching, since they are not 

contributing. Our goal was to encourage high contributors to avoid maxing out early, so they would not 

miss matching. 

Who were the participants? 

We contacted 1,602 employees who were on track to reach the elective deferral limit between late July 

and mid-November 2018. All participants were younger than 50, had no tax-exempt contributions, worked 

at agencies that used the National Finance Center for payroll transactions, and had at least one email 

address on file. 

How did the project work? 

Participants were randomly assigned into three groups: 

 30% received an email that included a personalized estimate of how much they were on track to 

miss in matching that year. 

 30% received an email that featured an estimate of what other people who reached the limit early 

had missed—and noted that roughly 1% of TSP participants reach the limit early. 

 The final 40% received a general education email about the elective deferral limit and how it can 

affect participant accounts. 

When did this project happen? 

Emails went out in mid-June 2018, followed by reminders in late July 2018. In 2019, we noted the total in 

each group who had not missed any matching during 2018, meaning that they adjusted their contributions 

successfully and were able to contribute for the entire year. We used both Chi square and two-sample 

proportion tests (two-tailed) to determine statistical significance. 

What were the results? 

At the end of the year, 38.0% of those who received the personalized email had missed no matching as 

had 36.0% of those who received the email with what others missed. In both cases, this was roughly a 

third higher than the general education email (28.0%) and statistically significant at the p < 0.001 and p < 

0.04 levels, respectively. Both approaches were better than the general education email, and the 

difference between the personalized approach and what others missed was not statistically significant.

 
Increasing contributions in automatically enrolled federal employees Year 2019 

What was the goal? 

We wanted to encourage participants who made no changes after being automatically enrolled at 3% of 

salary to increase their contributions. Since eligible participants receive matching on the first 5% of salary, 

saving more would provide interested employees with additional matching from their agencies. 

Who were the participants? 

We contacted 6,466 federal employees who had been automatically enrolled into the TSP between 2010 

and 2016 and had made no changes to the default contribution amount of 3% of salary. All participants 

worked at agencies that used the National Finance Center for payroll transactions, had at least one email 

address on file, and had no outstanding TSP loans. 

How did the project work? 

Participants were randomly assigned into three groups: 

 30% received an email that included a personalized estimate of how much they had missed in 

matching. 

 30% received an email that featured an estimate of what other people contributing 3% of salary 

had missed. 

 The final 40% received neither email at that time. 

When did this project happen? 

Emails went out in late March 2019, followed by reminders in late April and early June. In mid-July 2019, 

we noted the total in each group who had started contributing more than 3%, using both Chi square and 

two-sample proportion tests (two-tailed) to determine statistical significance. 

What were the results? 

After 31⁄2 months, 21.1% of those who received the personalized email had increased their contributions 

as had 19.8% of those who received the email with what others missed. In both cases, this was more 

than double the rate of those who received no email (8.2%) and highly statistically significant at the p < 

0.0001 level. Both approaches were better than no email, and the difference between the personalized 

approach and what others missed was not statistically significant. 

 

 
Encouraging catch-up contributions in high-contributing employees Year 2019 

What was the goal? 

We wanted to let participants approaching their 50th birthday know about catch-up contributions, which 

allow participants turning age 50 or older to contribute even more to the TSP. Since participants must be 

on track to reach the IRS elective deferral limit ($19,000 in 2019) to be eligible to make catch-up 

contributions, we focused on those who had gotten close to this limit the previous year. 

Who were the participants? 

We focused on 2,869 employees who 1) were turning age 50 during 2019, 2) had contributed at least 

$18,000 in 2018, and 3) had an email address and/or phone number on file. 

How did the project work? 

Participants were randomly assigned into four groups: 

 Of the 1,907 participants with phone numbers on file, roughly half received a phone call from a 

participant service representative explaining the importance of catch-up contributions. The other 

half received no phone call at that time. 

 Of the 962 participants who had an email address on file but no phone number, roughly half 

received an email explaining the importance of catch-up contributions. The other half received no 

email at that time. 

When did this project happen? 

Emails and phone calls went out in mid-May 2019. In July 2019, we noted the total in each group who 

had started making catch-up contributions, using both Chi square and two-sample proportion tests (twotailed) to determine statistical significance. 

What were the results? 

After two months, 15.2% of those reached by our participant service representatives had started making 

catch-up contributions, as had 15.8% of those who received our email. In both cases, this was roughly 

triple the rate of those who did not receive a phone call (6.2%) or email (4.8%) and highly statistically 

significant at the p < 0.0001 level. It is important to note that a portion of those we called did not answer. 

The 15.2% represents the response rate among those our representatives actually spoke to, so we 

interpret the results differently. 

 
Increasing saving in non-contributing federal employees Year 2019 

What was the goal? 

We wanted to encourage participants who were not contributing to their TSP accounts to start saving. 

Since eligible participants receive matching on the first 5% of salary that they contribute, saving more 

would provide interested employees with matching from their agencies. 

Who were the participants? 

We contacted 32,135 employees who were not contributing to the TSP at the time of our outreach. All 

participants worked at agencies that used the National Finance Center for payroll transactions and had at 

least one email address on file. 

How did the project work? 

Participants were randomly assigned into five roughly equal groups: 

 Group 1 received an email with a personalized estimate of how much they had missed in 

matching. 

 Group 2 received an estimate of what other non-contributors had missed. 

 We reminded Group 3 that their agencies automatically contribute an amount equal to 1% of 

salary to the TSP—and invited participants to contribute too. 

 We informed Group 4 that roughly 90% of federal employees contributed to the TSP. 

 Group 5 received no email at that time. 

When did this project happen? 

Emails went out in late September 2019, followed by a reminder in late October. In early January 2020, 

we noted the total in each group who had started contributing, using both Chi square and two-sample 

proportion tests (two-tailed) to determine statistical significance. 

What were the results? 

After 31⁄2 months, all groups who received an email were more likely to have increased their contributions. 

Compared to Group 5, Group 1 (personalized) was 21.4% higher, Group 2 (what others missed) was 

14.4% higher, Group 3 (reciprocity) was 15.9% higher, and Group 4 (social norms) was 17.8% higher. In 

all cases, these differences were statistically significant at the p < 0.0001 level. The personalized 

outreach was statistically higher than what others missed (p < 0.03), and no other differences between 

the emails were statistically significant. 
Increasing saving in non-contributing federal employees Year 2020 

What was the goal? 

We wanted to encourage participants who were not contributing to their TSP accounts to start saving. 

Since eligible participants receive matching on the first 5% of salary that they contribute, saving more 

would provide interested employees with matching from their agencies. 

Who were the participants? 

We contacted 19,846 employees who had not contributed any of their own money to the TSP during the 

calendar year. All participants worked at the Department of Veterans Affairs or the Department of Health 

and Human Services and had at least one email address on file. 

How did the project work? 

Participants were randomly assigned into five roughly equal groups: 

 The first three groups received an estimate of what other non-contributors had missed, along 

with instructions for how to make changes in their payroll system. 

o While the text was exactly the same, Group 1’s instructions were grouped into four longer 

steps, while Group 2’s instructions were presented as 8 shorter steps. 

o Group 3 received the longer steps as well as a closing salutation that thanked 

participants for being a part of the plan. 

 We reminded Group 4 that their agencies automatically contribute an amount equal to 1% of 

salary to the TSP—and invited participants to contribute too. 

 Group 5 received no email at that time. 

When did this project happen? 

Emails went out in mid-February 2020, followed by a reminder in early March. In early June 2020, we 

noted the total in each group who had started contributing, using both Chi square and two-sample 

proportion tests (two-tailed) to determine statistical significance. 

What were the results? 

After 31⁄2 months, all groups who received an email were more likely to have started contributing. 

Compared to Group 5, Group 1 (less steps) was 22.2% higher, Group 2 (more steps) was 24.3% higher, 

Group 3 (salutation) was 24.2% higher, and Group 4 (reciprocity) was 26.4% higher. In all cases, these 

differences were statistically significant at the p < 0.0001 level when compared to no email. 

Providing additional short steps appeared to be slightly better than providing half as many longer steps, 

and adding a salutation appeared to be more effective than not having one. However, none of the 

differences between approaches was statistically significant. 
Increasing saving in non-contributing federal employees Year 2020 

What was the goal? 

We wanted to encourage participants who were not contributing to their TSP accounts to start saving. 

Since eligible participants receive matching on the first 5% of salary that they contribute, saving more 

would provide interested employees with matching from their agencies. 

Who were the participants? 

We contacted 7,059 employees who had not contributed any of their own money to the TSP during the 

calendar year. All participants worked at agencies that used the Interior Business Center for payroll 

transactions and had at least one email address on file. 

How did the project work? 

Participants were randomly assigned into three groups. 

 30% received an email that included an estimate of what other non-contributors had missed in 

matching. 

 30% received an email pointing out that roughly 90% of federal employees contributed to the 

TSP. 

 The final 40% received neither email at that time. 

When did this project happen? 

Emails went out in late February 2020 with no reminders. In late May 2020, we noted the total in each 

group who had started contributing, using both Chi square and two-sample proportion tests (two-tailed) to 

determine statistical significance. 

What were the results? 

Compared to those who received no email after 3 months, those informed of what others missed were 

22.2% more likely to start contributing (p < 0.005), and those who learned how many others saved were 

33.6% more likely to start contributing (p < 0.0001). Both approaches were better than no email, and the 

difference between the social norms approach and what others missed was not statistically significant. 

 
Increasing contributions in automatically enrolled federal employees Year 2020 

What was the goal? 

We wanted to encourage participants who made no changes after being automatically enrolled at 3% of 

salary to increase their contributions. Since eligible participants receive matching on the first 5% of salary, 

saving more would provide interested employees with additional matching from their agencies. 

Who were the participants? 

We contacted 1,031 employees who had been automatically enrolled into the TSP during 2019 and had 

made no changes to the default contribution amount of 3% of salary. All participants worked at agencies 

that used the National Finance Center for payroll transactions and had at least one email address on file. 

How did the project work? 

Participants were randomly assigned into three groups: 

 30% received an email that included an estimate of what other non-contributors had missed in 

matching. 

 30% received an email pointing out that roughly 90% of federal employees contributed to the 

TSP. 

 The final 40% received neither email at that time. 

When did this project happen? 

Emails went out in early March 2020 with no reminders. In early June 2020, we noted the total in each 

group who had started contributing, using both Chi square and two-sample proportion tests (two-tailed) to 

determine statistical significance. 

What were the results? 

After 3 months, 20.6% of those who received what others missed had increased their contributions, as did 

23.7% of those who learned that 90% of federal employees were contributing. In both cases, this was 

more than double the rate of those who received no email (10.8%) and highly statistically significant at the 

p < 0.0001 level. Both approaches were more effective than no email, and the difference between what 

others missed and social norms was not statistically significant. 

However, we interpret these results with some caution because 44 participants were not available for 

follow-up, which is abnormally high. Of those 44 participants, 32 had left the federal government and 12 

were not paid during May 2020, perhaps due to voluntary leave without pay during the COVID-19 

pandemic.