Age last birthday is the formal version of the age-last method used in life insurance to determine an applicant's insurance age based strictly on the most recent birthday. Under this convention, an individual's insurance age changes only on their birthday, not halfway between birthdays. This age is used to select premium rates from carrier rate tables and can influence eligibility for age-banded products, riders, and underwriting programs. Compared with age-nearest methods, age last birthday can be advantageous for clients whose birthdays are near the application date because they are not prematurely rated as one year older. Age last birthday rules contribute to subtle but important differences in long-term premium costs across carriers.

Advisors and case designers reference age last birthday when explaining rate quotes and when timing applications around client birthdays. If a carrier uses age last birthday, advisors may encourage clients to apply shortly before a birthday rather than after, to lock in a younger insurance age for the life of the policy. They also compare age bases among carriers in spreadsheet case comparisons for large term or permanent cases. New business and illustration teams verify that the date of birth and effective date are correctly entered so the system applies an age last birthday calculation. Understanding age last birthday helps advisors answer client questions about why their age appears one year different on rate charts and to leverage age conventions as part of cost-optimization strategies.