Input controls serve to ensure the completeness, accuracy and authorization of input. To ensure completeness the following controls can be set up:
i. One for one checks i.e. each input is checked to output.
ii. Batch control totals and hash totals. These controls are often used where documents (e.g. invoices) are grouped together and processed in a single block.
A batch total is the sum of one of the numerical fields on the documents in the batch e.g. gross amount of the purchase invoice. This total is calculated normally and the documents are then input into the computer. The computer then calculates the batch total and this is compared with the manually calculated total. If they are different, then an error has occurred, perhaps an invoice value has been mis-keyed or a document may have been omitted from input altogether.
A hash total works in exactly the same way as a batch total but a different type of field is used e.g. the supplier code number. Unlike the batch total, the value of the hash total is meaningless but is still used for control purposes to detect errors on input or omissions.
B) Document counts.
C) Sequence checks.
D) Matching each master file record to a transaction record.
To ensure accuracy, the following controls can be set up:
i. Check digits
These are a means of control in that they ascertain whether or not a number is valid. A formula is used to calculate the number itself. The computer will then detect if the number is ever input correctly.
ii. Reasonableness: Checks to ensure data is within certain ranges.
iii. Existence checks: e.g. to check that the supplier account exists.
iv. Manual controls e.g. batch and arithmetic checks.
To ensure input is properly authorized, the following controls can be set up.
– Manual authorization
– Clerical review of transactions.
– One for one checking of amendments to standing data.
– Programmed checks on authorization limits