In the standard chart of accounts 7100 is rent and is grouped into premises costs with 7101, 7102, 7103 etc.
the chart of accounts can be altered and it sounds like someone may have already changed it, if 7100 is missing.
If you go into CoA then select Edit in the next screen, you will see the layout of the chart of accounts. If you then select Overheads, you should see Rent & Rates, which should have a range of 7100 to 7199
This assumes that the standard chart of accounts is being used. It is also not adviseable to change anything unless you are sure what you are doing, otherwise some items may not be included in the statements (or be in the wrong place). You can check to see if any N/C are missing from the reports by clicking the "Check" button, which will run a report of N?C that are in the main Nominal list but are not included in the CoA.
Yes, if the POAs have been allocated to the landlord as a supplier, but no invoices have been posted, then there will be no rent expense and you'll have a - balance on the creditors report.
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Jenny
Responses are my opinion based on the information provided. All information should be thoroughly checked before being relied on.