Not to be a nihilist, but 200 seems like a ridiculously and surprisingly low number for impact of such an expensive and broad program. Does it really validate what the author posits?
“The final sample consists of 4.5 million returns, corresponding to 8.9 million individuals. Individuals in the sample were randomly assigned to receive a letter (86%) or to a control group (14%). One letter, addressed to the taxpayer(s), was sent per return. Hence, randomization was conducted at the household level.”
So 86% of 4.5 million households were sent a letter, and that led to a 1.3% percentage point increase in signups compared to the 14% of households that were not sent a letter. They are then saying that those 1.3% of extra signups led to saving ~700 lives. There is the risk of a selection bias because we don’t know why those extra 1.3% signed up versus those that didn’t.
The actual paper uses months, since everyone dies, so zero lives can be saved in the long term.