  Pursuing educational qualifications later in life is an increasingly common
phenomenon within OECD countries since technological change and automation
continues to drive the evolution of skills needed in many professions. We focus
on the causal impacts to economic returns of degrees completed later in life,
where motivations and capabilities to acquire additional education may be
distinct from education in early years. We find that completing an additional
degree leads to more than \$3000 (AUD, 2019) extra income per year compared to
those who do not complete additional study. For outcomes, treatment and
controls we use the extremely rich and nationally representative longitudinal
data from the Household Income and Labour Dynamics Australia survey (HILDA). To
take full advantage of the complexity and richness of this data we use a
Machine Learning (ML) based methodology for causal effect estimation. We are
also able to use ML to discover sources of heterogeneity in the effects of
gaining additional qualifications. For example, those younger than 45 years of
age when obtaining additional qualifications tend to reap more benefits (as
much as \$50 per week more) than others.
