Don’t leave the GR/IR analysis to the year end! Check it throughout the year as it is easier to correct items near the time of posting to keep the stock and moving average prices accurate.
Consider using the GR-based invoice verification setting to match invoice against deliveries rather than PO line item. But, as you have to have the goods receipt before the invoice can be posted, you may want to switch it off the goods receipt invoice verification setting if invoices may be received before the goods receipt via an interface.
Make sure the master data is accurate, in particular set the GR/IR account to post automatically only, to show open items and line items, and ensure the sort key allows the PO number and the line item number to appear on the GR/IR account.
Set the duplicate invoice check as mandatory in the vendor master to reduce duplicates
Look into tolerances, you do not want to spend too much time on small differences, they can be written off directly. Maybe you want a larger tolerance for intercompany than third party vendors.
Consider scheduling jobs like MRBR to run overnight in automatic mode and also F.13 to clear matched open items on the GR/IR account.
Ensure that the user parameters contain an X against parameter IVFIDISPLAY if you want users posting an invoice to see both the MM and FI document.
In MIR5 use the icon “expert mode” to see FI documents displayed in the list as well as MM.
Ensure that credit memos are used for quantity postings and subsequent credits and debits for price adjustments.
If you have currency exchange issues when clearing the GR/IR with F.13, consider F13E (or expanding the selections on F.13) to clear in a different currency.
Ensure that users cannot manually remove the “R” block, i.e. the block set by the 3-way matching, partly to keep MRMR and your open items in sync, and also to ensure that the quantity blocks are not removed from the invoice without correcting the balance on the GR/IR account.
Don’t use MRBR for quantity to manually remove quantity blocks without ensuring that the proper posting is carried out (e.g. additional goods receipt or credit) to correct the GR/IR balance.
You can reverse an MR11 document using transaction MR11_SHOW but only the whole document not individual items.
Consider the report MBEXPLAINWRX in OSS note 2139101.