Hope this is not too late. See if the following command works.
Suppose your client folders A, B, C, ..., 0, 1, ...9 all reside in a parent folder called "c:\Client Folder" (which of course can be a drive on the network or server). Open a command prompt window and type and enter:
for /r c:\"client folder" %1 in (tax, "accounting services", "corporate finance", "any other subfolder") do if exist %1 md %1\2004 %1\2005 %1\2006
The command - for /r c:\"client folder" - asks the computer to go through the entire directory tree headed by c:\client folder.
%1 is the variable, to be matched against the items in the set (the brackets) separated by commas and spaces (tax, "accounting services", ...).
Then do: if these folders exist, then md (make directory).
So the entire command is to go through the C:\client folder to look for the folders tax, accounting services and so on. If these folders exist, then make the directories 2004, 2005, 2006 immediately underneath the relevant %1 folder.
Folder names with spaces in between should be enclosed with quotation marks.
You can test it out on a test folder with its own subfolders first. I've tested it on my Windows 2000 machine and it works. I think these commands are the same in NT4. Double check the NT4 command reference.
You can do this in a command prompt. Or you can create a batch file (not really necessary since it's only one single command). In a batch file I think the variable should be %%1 instead of %1.