Return the last day of the current quarter

You can return the last day in the month by using the EOMONTH function.
Cell "A1" displays a date.
All these cells have been formatted with the custom number format "dd dddd mmmm yyyy".

	A
1	=TODAY() = 01 Thursday December 2022
2	=EOMONTH(A1,MOD(3-MONTH(A1),3)) = 31 Saturday December 2022

Built-in Functions

EOMONTH - The date serial number of the last day of a month before or after a date.
MOD - The remainder after division.
MONTH - The month as an integer given a date serial number.
TODAY - The date serial number representing today's date.

Related Formulas

Return the current quarter