ACCOUNT,DATE,NOTE
H123456,20151209,THIS IS A TEST

##</code><code>##

use strict;
use warnings;

my %reformat;
my $re = qr{^(H\d+,\d+,)(.*)$};


	open (NEW, ">", "Notes_Test_OUTPUT.txt" ) or die "could not open:$!";
	open (FILE, "<", "Notes_Test.txt") or die "could not open:$!";

	while (<FILE>) {
    	chomp;
    	/$re/;
    	push @{ $reformat{$1} }, $2; 
}

	print NEW if $_, join ' ', @{ $reformat{$_} } for keys %reformat;

close (FILE);
close (NEW);