DateDiff is counting 13 months for previous year

[kmax]

Hi,
I am working to count number of months as below.

StartDate           EndDate          TotalMonths
26-dec-2023     25-dec-2024    13
30-nov-2023     30-nov-2024    13
01-jan-2024      31-dec-2024    12

Dax formula is 
DATEDIFF(
StartDate,
EndDate,
MONTH
) +1
If I remove +1, it shows 11 months for current year data. Adding +1 in datediff works fine for current year but adds an extra month where startdate is in previous years.
How can I fix this issue.
Thanks in advance

[Vallirajap · Accepted solution]

Hi @kmax 

Try this, you can use the below dax to create  a new measure to solve the issue.

Total Months = DATEDIFF([StartDate]-1, [EndDate], MONTH)

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Hit the kudo also,

Thank you.