A line in the wrong month changes your profit, not just your stock.

I am the finance manager at an industrial distributor, closing September 2026. I have 4 files:
the September close figures, warehouse receipts, supplier bills, and shipments with their invoices,
all from 23 Sep to 7 Oct.
The stock system counts a receipt the day it arrives and a shipment the day it leaves.
The books count a receipt when the supplier bill is posted, and a shipment when the invoice is posted.
1. Match every receipt to its supplier bill by PO, and every shipment to its invoice by sales order.
2. List every pair where the 2 dates fall in different months, and every receipt with no bill.
3. Put each line in one of 4 groups: received in Sep, billed in Oct or not yet / billed in Sep, received in Oct /
   shipped in Sep, invoiced in Oct / invoiced in Sep, shipped in Oct.
4. For each group: the value at cost, and whether it makes the books higher or lower than the stock system.
5. Add the 4 groups. Compare with the difference between the stock system and the books at 30 Sep.
Do not round. Show your working.

Now show what these lines did to September.
Ownership passes when the goods arrive, and a sale counts when the goods ship.
1. For each group: is September's inventory, accounts payable, sales and cost of sales too high or too low, and by how much?
2. Write the entries that put each line in the right month.
3. Show September as posted and as it should be: inventory, accounts payable, sales, cost of sales, gross profit.
4. Rank the lines by their effect on gross profit. Next to each, write the one question to ask and who to ask.

Here are the column names from my [SYSTEM NAME] exports.
Receipts: [PASTE THE HEADER ROW]. Supplier bills: [PASTE]. Shipments and invoices: [PASTE].
Match each one to: date received, PO, bill date, period posted, sales order, ship date, invoice date,
cost value, invoice amount.
Tell me which ones are missing and what I would need to export to get them.
Do not guess a match. If unsure, ask.