Issue
 When you import a G/L budget from Excel, the amounts are imported into the wrong periods in the North American version of Microsoft Dynamics NAV 2013. For example, January amounts are imported into December, February amounts are imported into January, etc. 
Solution
 Cause
This problem is caused by the way the .net variable DateTimeHelper.FromOADate(Decimal) function handles time zones.

Resolution
  1. Add the line of code in bold to the ParseCellValue  function in table 370 - Excel Buffer:  
     
    IF ((STRPOS(FormatString,'y') <> 0) OR  
    (STRPOS(FormatString,'m') <> 0) OR  
    (STRPOS(FormatString,'d') <> 0)) AND  
    (STRPOS(FormatString,'Red') = 0)  
    THEN BEGIN  
    // Excel Date is stored in OATime format  
    Decimal += 0.5; // Add time offset to help FromOADate select the correct date.  
    DateTime := DateTimeHelper.FromOADate(Decimal);  
    "Cell Type" := "Cell Type"::Date;  
    "Cell Value as Text" := FORMAT(DT2DATE(DateTime));  
    EXIT;  
    END;
Refer to https://mbs2.microsoft.com/Knowledgebase/kbdisplay.aspx?WTNTZSMNWUKNTMMYVWQXNRNXTVKNSKYVSSYWTSMSMUQSNKWW