NACHA File to Excel Converter: Convert ACH Files to CSV and Excel

What is a NACHA file?

A NACHA file is the fixed-width text file US banks and businesses use to move ACH payments: payroll direct deposits, vendor payments, insurance premiums, and collections. Nacha's own developer guide puts it plainly, an ACH file is a fixed-width ASCII file with each line exactly 94 characters long. Payroll systems and ERPs generate one, the originating bank passes it to an ACH Operator, and the receiving bank posts the entries. People call it an ACH file and a NACHA file interchangeably. They mean the same thing, since NACHA is the rule-making body whose format the file follows.

NACHA file format: the records inside

Every ACH file is a nest of records, each starting with a one digit code that tells software what the line is. A file holds one or more batches, each batch holds its entries, and every header record has a matching control record that closes it. Here is what each code marks.

Two structural rules explain most of the confusion. Alphanumeric fields are left justified and space padded, while numeric fields are unsigned, right justified, and zero filled. And ACH files use a blocking factor of 10, so the file is padded with lines of 9s until the line count is a multiple of ten.

If you need every field rather than the summary, the NACHA file format reference documents all six record types position by position, including the addenda, batch control and file control layouts and the transaction and SEC code tables.

What is inside an ACH entry detail record

The type 6 record is the one you actually want in a spreadsheet, because it is the payment. Per published bank ACH specifications, the standard CCD and PPD entry detail layout divides those 94 characters like this.

One warning worth repeating. A CTX entry uses positions 55 to 76 for the addenda count and the receiving company name rather than an individual name, so a converter that assumes every file is PPD will mislabel a corporate trade exchange file.

CTX matters for a second reason. Its addenda records are where X12 remittance data rides along with the money, so the payment detail explaining which invoices a vendor payment covers is often an EDI 820 wrapped inside the ACH file. If your bank hands you that remittance as a separate file rather than as addenda, the EDI 820 to Excel converter turns it into one row per invoice.

ACH transaction codes you will see in the data

The two digit transaction code at positions 02 and 03 is what tells you whether money moved in or out and from which kind of account. These are the ones that show up in most corporate files.

SEC codes in the batch header

The three letter Standard Entry Class code at positions 51 to 53 of the batch header says what kind of authorization sits behind the entries. It matters when you convert, because it changes how the entry rows should be read.

What changed in ACH files for 2026

Two rule changes are worth knowing before you review a current file. As of March 20, 2026, two company entry descriptions became mandatory in the batch header at positions 54 to 63: PAYROLL on PPD credits that pay wages or salaries, and PURCHASE on WEB debits for e-commerce purchases. If you are converting files to check compliance, that field is now a real test rather than free text.

Nacha also phased in fraud monitoring requirements during 2026. Phase 1 took effect March 20, 2026 for all ODFIs and for larger non-consumer originators, third-party senders, and receiving institutions. Phase 2 extended the requirement in June 2026 to all non-consumer originators, third-party senders and service providers, and all receiving institutions regardless of volume. Separately, the Same Day ACH limit is still $1 million per payment; Nacha has approved an increase to $10 million, but that does not take effect until September 17, 2027.

From an ACH file to your accounting or treasury system

Once the entries are rows, the rest is ordinary spreadsheet work. For the manual routes as well, including the fixed-width import and a Power Query approach, see our full walkthrough on how to open a NACHA ACH file in Excel or convert it to CSV. Going the other direction, building a file rather than reading one, is covered in how to create a NACHA file in Excel. If your bank also sends balance reporting, the BAI to Excel converter handles those files, and the MT940 to Excel converter covers SWIFT statements. Loading the result elsewhere? Map it through the bank statement OFX converter, the QuickBooks QBO format, or, for enterprise teams, the NetSuite bank statement converter and the SAP bank statement converter. If you only have the PDF statement rather than the ACH file, the general bank statement converter produces the same structured rows, and bank statement reconciliation covers the tie-out.

How do I create a NACHA file in Excel?

You cannot save a spreadsheet as a NACHA file directly. A NACHA file is a fixed width text file of 94 character records, and Excel has no export that produces that shape, so building one means assembling the record structure yourself: a file header, then for each batch a batch header, one entry detail record per payment, any addenda, a batch control record, and finally a file control record, with filler lines added so the total record count is a multiple of ten. The formatting rules are unforgiving. Amounts are written in cents with no decimal point, every field pads to an exact width, and the entry hash and totals in the control records have to agree with the entries above them or your bank rejects the file.

In practice most US businesses should not hand build the file. Originate through your bank portal or ACH software, which validates before transmission, and use Excel to stage the payment list. If you do build one, keep the source data in a sheet and generate the fixed width output from it rather than typing records, and read how to create a NACHA file in Excel and how to validate a NACHA file before sending it first, then run the result through the NACHA file validator so the control totals are checked before your bank sees it. The check equivalent of this exercise, the issued check list you upload for fraud matching, follows a different set of bank specific rules covered in the positive pay file format reference.

After the data is in a spreadsheet

Most teams do not stop at Excel. If the next step is QuickBooks Online, you can turn the exported file into an importable QBO with a CSV to QBO converter. Finance teams that need to chase the invoices behind those vendor payments can automate the follow-up with accounts receivable automation, and teams processing other finance documents at volume can extract them with enterprise document OCR.