Before you can pay or create accounting entries for any invoice, the Invoice Validation process must validate the invoice.

Invoice Validation checks the 

1. period status
2. tax
3. exchange rate
4. distribution information
5. matching(IMO, invoice matching option)
   
6. tollerence

Invoice validation does the following job
1. It creates/modifies the payment schdule on the basis of payment term and term date basis.
2. Invoice validation is a accounting event. so after the completion of it we can create accounting. It checks the supplier site to determine which invoice tolerance template to use. If no invoice tolerance template is specified, tolerance checking is not performed. If an invoice tolerance template is specified, Invoice Validation will check against the specific invoice tolerances template stored in the Invoice Tolerances window to determine if the invoice falls within the defined tolerances and automatically applies holds to exception invoices.
If an invoice has a hold, you can release the hold by correcting the exception that caused Invoice Validation to apply the hold by updating the invoice or the purchase order, or changing the invoice tolerances. Then resubmit Invoice Validation to release the hold. In the Invoice Holds tab, you can manually release certain invoice holds, even if you have not resolved the matching error condition.

Note: When the invoice is in a Validated state, the Liability Account field cannot be updated.

1. Authorized users can always correct an invoice, even if you have validated, approved, paid, or created accounting entries for the invoice.

2. You can identify all invoices that Payables has not yet reviewed with Invoice Validation by submitting the Invoice Register and selecting the Unvalidated Invoices Only parameter. You can review the validation status of an invoice online in the Invoice Overview window or the Invoices window.

3. Payables and Oracle Alert integrate to alert the appropriate accounts payable or purchasing staff when you or Payables place an invoice on hold. Oracle Alert also provides an integrated system of alerts, messages, and message distribution to focus attention on time-sensitive or critical information and streamline the validation process.

Exception reporting in Oracle Alert is accomplished using either electronic mail or paper reports.

4. You can submit an invoice for validation in one of the following ways:

• Online by using either the Validate or the Validate Related Invoices check box in the Invoice Actions window.
• Online by using the Validate button in the Invoice Batches window.
• Batch by submitting the Payables Invoice Validation program from the Submit Request window.

5. The order of the Invoice Validation process and Invoice Approval Workflow Program is based on the Approval Processing Sequence Payables option. For example, you might want to validate before you approve if you enter invoices that require the Invoice Validation process to create tax distributions for you. If your approvers need to review tax details before they approve an invoice, then we recommend that you select an option that validates before approving. For more information on submitting invoices for approval.

Validation Example
Invoice Validation places three invoices on matching hold. The first invoice is on matching hold because the quantity billed exceeds the quantity received. The second invoice is on matching hold because the invoice price exceeds the purchase order shipment price. The third invoice is on matching hold because the quantity billed exceeds the quantity ordered.

Invoice 1. Your receiving department receives the goods and records the receipt information. Your invoice now matches the receipt and Payables releases the hold when you submit Invoice Validation.

Invoice 2. A supplier sends a credit to correct the amount due on a previous invoice.
You match the credit to the purchase order as a price correction and associate it with the invoice during the match. The weighted average price of the invoice and credit memo now matches the purchase order shipment price. Payables releases the hold when you resubmit Invoice Validation. Use the Validate Related Invoices option in the Invoice Actions window to submit Invoice Validation for both the credit and the original invoice.

Invoice 3. You increase your tolerance levels using the Invoice Tolerances window.
Your invoice now matches your receipt and purchase order within your newly-defined tolerance levels and Payables releases the hold when you resubmit Invoice Validation