CAAT means Computer Assisted Audit Techniques. There are two main types:
1 Audit software. This software belongs to the auditor and is used to read clients’ files. It can be used to identify noteworthy transactions, select samples and for reperformaing calculations (such as adding up the file).
2 Test data. This is data designed by the auditor and which is operated on by clients’ programs to see what the results are. For example, try to process a transaction that would put a customer over their credit limit and see if the client’s system rejects it.