Creating table with month days and checking if workdays

[ErikJan]

I'm creating a small table in Excel where I have the Months on top (Jan > Dec, month numbers 1 through 12) and the days in rows.
I've pulled all the rows down to 31 for the days.

What I like to do is highlight the work days in this year-table (adjusting for holidays).

I found a formula to check if a date is a workday: =WORKDAY(date-1,1,holidays)=date

And that works. However in my table I -obviously- have non-existing dates in my setup (like e.g. June 31). As I build the date for the formula above using the "Date"-function (like: Date(Year, Month, Day)), when I enter resp. 2022, 06, 31, Excel is clever enough to return July 1st.
Now that's nice, but it defeats the formula above and now flags this date as a working day...

Of course I can eliminate June 31st (and other non-existing dates) from my table manually, but I'd like Excel to automatically flag non existing dates as non-workdays as well (think e.g. leap years and Feb 29th).

Any suggestions how I can do this, i.e. how do I find out that a date is not possible?

[HansV]

Let's say you have year in K1, month number in L1 and day number in M1.The formula
=MONTH(DATE(K1,L1,M1))=L1
returns TRUE if the date in K1,L1,M1 is a "real" date and FALSE otherwise.
So if K1=2022, L1=2 and M1=29, the formula returns FALSE, but if K1=2024, L1=2 and M1=29, the formula will return TRUE.
Can you adapt this for your purpose?

[ErikJan]

I think so... Nice approach, thanks!

[ChrisGreaves]

returns TRUE if the date in K1,L1,M1 is a "real" date and FALSE otherwise.