This final rule provides a simplified measure of capital adequacy for federally insured, natural-person credit unions (credit unions) classified as complex (those with total assets greater than $500 million). Under the final rule, a complex credit union that maintains a minimum net worth ratio, and that meets other qualifying criteria, is eligible to opt into the complex credit union leverage ratio (CCULR) framework if they have a minimum net worth ratio of nine percent. A complex credit union that opts into the CCULR framework need not calculate a risk-based capital ratio under the NCUA Board's October 29, 2015 risk-based capital final rule, as amended on October 18, 2018. A qualifying complex credit union that opts into the CCULR framework and maintains the minimum net worth ratio is considered well capitalized. The final rule also makes several amendments to update the NCUA's October 29, 2015 risk-based capital final rule, including addressing asset securitizations issued by credit unions, clarifying the treatment of off-balance sheet exposures, deducting certain mortgage servicing assets from a complex credit union's risk-based capital numerator, revising the treatment of goodwill, and amending other asset risk weights.