ACH Bank File Format

I don't know which Topic Area to ask this in, but since this is where the data experts live, I'll ask here. :)

We are trying to find the dataspec / file format that banks and other financial institutions (such as Electronic Funds Transfer services) use to move money around. In other words, we need the ACH data spec.

I have "Googled" until my eyes fell out and all I can find are services and applications that have the ability to export to the ACH file format. Of course, that is not what we want... we want the file format so that we can generate our own files and upload them to a bank.

Has anyone seen the file format / data spec for ACH files and if so, can you point me to it? I have checked the American Banker's Association ( but they are not much help if you are not a member. We are not a bank... we are developers looking to generate a file and upload it to a bank.
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arbertConnect With a Mentor Commented:
Ya, forget about aba....Take a look at NACHA.ORG.....You're going to have to shell out a little bit of money--there are many standards and several books you can buy....

The standards are easy, but they change every now and again, so it's not a bad idea to get on their list or become a member.

I don't believe there is any one "standard" ACH file format to send to banks.  When there is a standard XML format that all banks agree on, we can all rejoice and dance in the streets.  I wouldn't hold my breath, though; we're talking about banks here.  I think every bank has their own file format.

We upload a file to our bank, but they supplied the documentation for their particular processing system.  Depending on who your bank is and how important they think you are, you may be able to get this information .  If you are trying to develop some sort of generic ACH system, good luck.  I don't know how much use that NACHA stuff would be, because the banks connect directly to the ACH network, not you.  You send data to your bank, which then processes it and sticks it on the network.
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It does depend on your bank.  However, all banks (unless there some little podunk bank) should accept a NACHA standard file.  When the reprocess your file, not matter what format it is in, to send to the FRB, the convert it into a NACHA format anyway........
whatsit2002Author Commented:
The bank(s) we are going to be uploading files to told me, "... we can't seem to find the data spec for that file..." because they wanted us to use a third party software package. I asked them if they took NACHA files and they said yes. I told them that I could get the rules book (which includes the file format, according to NACHA) for US$55, and they told me to do that since they couldn't "find" their copy of the file format. Such is life, I guess.

arbert, you win the points since you turned me on to NACHA. ctcampbell, thank you for your input. It is greatly appreciated as well. Also, as far as becoming a NACHA member, it costs about $1200 per year. I say (watch out... really bad pun ahead), for that kind of money, they better give you a lot of NACHA cheese. ;)

Thanks again.

Ya, 1200.00 isn't that much when you have a large company paying for it :)  As long as you have your book of rules you'll be ok.

Last company I worked for, we traded files directly with the FRB at first.  Then, we started trading with a local bank and the switchover was pretty transparent--the file worked for both.
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