SQL Partition Function without actual values
You cannot create a dynamic VALUES clause in a CREATE PARTITION FUNCTION statement.  An alternative is to use the ALTER PARTITION FUNCTION statement to add a new range to the function.

I've encapsulated the required statements into a stored procedure:

IF OBJECT_ID(N'dbo.partition_function_add_date_range', N'P') IS NOT NULL
DROP PROCEDURE dbo.partition_function_add_date_range;
GO
CREATE PROCEDURE dbo.partition_function_add_date_range
(
      @function_name sysname
    , @range_date datetime
    , @scheme_name sysname
    , @next_filegroup sysname
)
AS
BEGIN
    SET NOCOUNT ON;
    IF NOT EXISTS (
        SELECT 1
        FROM sys.partition_functions pf
        INNER JOIN sys.partition_range_values prv ON pf.function_id = prv.function_id
        WHERE pf.name = @function_name
            AND prv.value = @range_date
        )
    BEGIN
        DECLARE @cmd nvarchar(max);
        SET @cmd = N'ALTER PARTITION SCHEME ' + QUOTENAME(@scheme_name) + N' NEXT USED ' + QUOTENAME(@next_filegroup) + N';';
        PRINT @cmd;
        EXEC sys.sp_executesql @cmd;
        SET @cmd = N'ALTER PARTITION FUNCTION ' + QUOTENAME(@function_name) + N'() SPLIT RANGE (''' + CONVERT(nvarchar(max), @range_date, 120) + N''');';
        PRINT @cmd;
        EXEC sys.sp_executesql @cmd;
    END
END
GO


An example of how to call this stored procedure:

EXEC dbo.partition_function_add_date_range @function_name = N'DateRangePF '
    , @range_date = '2018-01-01 00:00:00'
    , @scheme_name = N'DateRangeSC'
    , @next_filegroup = N'PRIMARY';


This could be added to a SQL Server Agent Job, scheduled to run once a year, prior to rows being inserted into the new fiscal year.  The job step command would run something like this, which will automatically add the next year to the partition function, and any associated tables.  

DECLARE @daterange datetime;
SET @daterange = CONVERT(varchar(30), DATEPART(YEAR, GETDATE()) + 1) + '-01-01 00:00:00';
EXEC dbo.partition_function_add_date_range @function_name = N'DateRangePF'
    , @range_date = @daterange
    , @scheme_name = N'DateRangeSC'
    , @next_filegroup = N'PRIMARY';


It's important to realize partition function modifications will affect ALL tables that use the partition function.