一个关于cash balance pension plan的问题

is the crediting rate of cash balance pension add to the polilcyholder's account at the beginning of the year or the end of year. Also, if the crediting rate is set to an index (ex, 20-yr treasury rate), during the time period t - t+1, is it decide at the beginning of the year (which will be constant at t) or at the end of the year (which is unknown at t)?