Base year
\beɪs\ \jɪr\
The reference year for a base table.
The base year is the effective date for the mortality rates and the year from which mortality improvements are assumed to start.
Example:
A mortality table with the base year of 2012 means the mortality rates in the table were built using data from a range of years centred / centered around 2012 (e.g., 2010-2014). The expected rates reflect conditions as of 2012, and any future projections, such as generational improvements, are applied from that year onward.