In crude death rate the population is taken as on -
1st March
1st July
1st April
15th August
A rate comprises the following elements →

i) Numerator
ii) Denominator
iii) Time specification       
iv) Multiplier
Numerator → Refers to the number of times an event (e.g. sickness, birth, death) has occurred in a population, during a specified time period. Numerator is a component of the denominator in calculating a rate, but not in a ratio.
Denominator → Denominator may be :-
i) Related to population
Mid year population → population estimated on first of July of an year
Population at risk
Person - time
Person distance
ii) Related to total events
 As in case fatality rate, denominator is total number of cases rather than total population.