diff --git a/README.md b/README.md
index 81a4bf6..8e1ce38 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,39 @@
 # Process CSV reports
 
+The processing script `process_report.py` takes in the monthly invoices and goes through several processing and exporting steps:
+1. Combines all provided invoices (more info below)
+2. Obtain each PI's institution name
+3. Exports the list of non-billable projects (more info below)
+4. Apply the New PI credit (more info below)
+5. Exports the billable projects as one csv, by PI, for HU PIs only, for HU and BU PIs, and for projects with Lenovo SU Types
+
+The CSV invoices must at least contain the following headers:
+- Invoice Month
+- Project - Allocation
+- Manager (PI)
+- Institution
+- SU Hours (GBhr or SUhr)
+- SU Type
+- Cost
+
+```
+usage: process_report.py [-h] --pi-file PI_FILE --projects-file PROJECTS_FILE --timed-projects-file TIMED_PROJECTS_FILE [--output-file OUTPUT_FILE]
+                         [--output-folder OUTPUT_FOLDER] [--HU-invoice-file HU_INVOICE_FILE] [--HU-BU-invoice-file HU_BU_INVOICE_FILE] [--old-pi-file OLD_PI_FILE]
+                         csv_files [csv_files ...]
+process_report.py: error: the following arguments are required: csv_files, --pi-file, --projects-file, --timed-projects-file
+
+E.g. python process_report.py test1.csv test2.csv --pi-file pi.txt --projects-file projects.txt --timed-projects-file timed_projects.txt --output-file myfile.csv
+```
+
+## New PI Credit
+Applies the New PI credit, which is a credit applied for PIs who have not created a project on the NERC. An file containing a list of known PIs and their date of first appearace must be provided
+
+The file of old pis may look like this:
+```
+alice@example.edu,2024-01
+bob@example.com,2023-11
+```
+
 ## Non-Billable
 
 Automates the process of removing non-billable PIs and projects from the supplied csv report.
@@ -33,16 +67,6 @@ bo@example.com,project bar,2023-09,2024-08,Internal
 The script will gather the invoice month from the csv reports and if it falls under the start and end date then those projects will be excluded.
 In this example, `project foo` will not be billed for September 2023 and August 2024 and all the months in between for total of 1 year.
 
-The CSV report must have the headers `Manager (PI)'` and `Project - Allocation'`.
-
-```
-usage: process_report.py [-h] --pi-file PI_FILE --projects-file PROJECTS_FILE --timed-projects-file TIMED_PROJECTS_FILE [--output-file OUTPUT_FILE]
-                         csv_files [csv_files ...]
-process_report.py: error: the following arguments are required: csv_files, --pi-file, --projects-file, --timed-projects-file
-
-E.g. python process_report.py test1.csv test2.csv --pi-file pi.txt --projects-file projects.txt --timed-projects-file timed_projects.txt --output-file myfile.csv
-```
-
 ## Combine CSVs
 
 This script also combines the 3 separate Invoice data CSVs into 1 Invoice CSV. It combines