From what you've said I gather you simply want to calculate someones age given their birth date and the present date? then the formula is simply:

=DATEDIF(A1,A2,"y")

Note that the date format doesn't matter if either or birth date and present date are in the date format you specified "MM/YY" or "DD/MM/YYYY" as LibreOffice Calc always stores the full date. See attached image.

I created this formula in Excel so I know it works in both Excel and LibreOffice, to calculate how long I had worked in my last job to the present date and I needed to also calculate the months and the days. As you will see in the attached image. For demonstration purposes I have modified the formats of the start date and end dates, the start date is in the format DD/MM/YYYY and the end date MM/YY. Note that my formula takes into account if there are 0 Years, or only 1 Year, or more than one year, so it reads 0 Years, or 1 Year or 2 Years as the case may be.

So to calculate the years, months and days individually as per my example:

Years:
=DATEDIF(B3,B6,"y")&IF(DATEDIF(B3,B6,"y")<>1," Years"," Year")

Months:
=DATEDIF(B3,B6,"ym")&IF(DATEDIF(B3,B6,"ym")<>1," Months"," Month")

Days:
=DATEDIF(B3,B6,"md")&IF(DATEDIF(B3,B6,"md")<>1," Days"," Day")

where "ym" restricts the result to months in the year, ignoring the years and likewise, "md" restricts the result to days in the month, otherwise using "m" or "d" it would literally return the total number of months and days elapsed between the 2 dates and in this case it would be undesired!

Or to concatenate the years, months and days into a one shot formula, simply separate each formula with and ampersand as shown below:
=DATEDIF(B3,B6,"y")&IF(DATEDIF(B3,B6,"y")<>1," Years"," Year") & ", " &DATEDIF(B3,B6,"ym")&IF(DATEDIF(B3,B6,"ym")<>1," Months"," Month") &" and " & DATEDIF(B3,B6,"md")&IF(DATEDIF(B3,B6,"md")<>1," Days"," Day")

I trust that should answer your question and also help anyone else who is looking for a formula to calculate how someones age, or precisely how long someone has worked in their job, including months and days or whatever the case may be.

Also note that it doesn't matter to LibreOffice Calc, if either the start date or the present date is just a date DD/MM/YY or calculated, say with:

=TODAY()

or

=A1+14

since the result will still be a date!

Please always write what exactly did you try (what exact formula(s) in this case), to enable others to see what's the problem actually. Because if you have proper dates (not texts), then the formula

`=DATEDIF(A1;A2;"y")`

works for me.My problem is that I have only one cell as reference - the other date is current date.

`=DATEDIF(C1;NOW() ;"y")`

raises`#VALUE!`

And

`=DATEDIF(C6;NOW('mm/yyyy') ;"y")`

raises`Err:508`

Is C6 a proper date? Does it show you the date in the "sum" statusbar area? or is it a string actually?

As I said, it is a date in format

`MM/AAAA`

(I have only month and year of birth), for example`05/2009`

What you said didn't explain much. It could be a proper date (with cell formatting only showing the said date parts; btw, you use some localized characters for year that is usually shown as YYYY); or it could be the string looking like a date, but having no meaning as date (which seems to be your case). If it's just a month+year, then you can as well use the first day of a month and setup the display format. Then it will work.

If you only have month/year and DATEDIF() gives a #VALUE! error, then that likely are not proper dates but strings instead. To calculate with dates you need dates instead of strings. So enter the birth date including the day of birth.