Can I still invoice last month's work after the month has ended?

Yes. Give the invoice an earlier Invoice date; it cannot be later than today. Do it before you export the month.

Can I see what customers owed on the last day of the month?

Yes. Set As of on Receivables ageing to that day; payments and credit notes dated after it are not taken off.

Why does an invoice the customer has paid still show a balance?

The money may be on the account as unapplied, for example from a payment recorded without ticking the invoice. The invoice keeps its Balance due until you allocate the money to it with Allocate to invoices.

Month-end checklist

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Half an hour on the first working day of the month keeps your receivables clean and gives your accountant a complete month. Work in this order: each step tidies what the next one reads.

How to do it

Issue or delete drafts left open. On Invoices, set the Status filter to Draft. Issue the ones for work done last month: the Invoice date can be earlier than today, such as the day you delivered. Delete the ones that will never go out.
Use unapplied money. In Reports, open Receivables ageing: a customer tagged Credit has paid more than they owe. On any account you open, a note at the top of the Invoices tab counts unapplied payments. Open the receipt and select Allocate to invoices, or refund the money if the customer asks.
Review what is overdue. Set As of on Receivables ageing to the last day of last month, then send statements to the customers with late balances.
Export the month for your accountant. Open Accounting export under System settings; the Period opens on last month. For bank charges and write-offs, also download Payment differences (CSV) from the Invoices list’s ··· menu.

Why it helps

A draft is not a sale yet: it is left out of statements, reports and the accounting export, so a forgotten draft is work nobody is billed for. Unapplied money makes a customer look as if they still owe on invoices they have paid. And an export is a set of files for one period: an invoice issued afterwards with a date in that month is not added to the file you already sent. Tidying first means the export is complete the first time.

Example

On Monday 2 November 2026, Priya Nair runs Lim & Co’s month end.

Drafts. Two drafts are open. One is for lighting delivered on 30 October; she issues it dated 30 October. The other duplicates an issued invoice, so she deletes it.
Unapplied money. Receivables ageing, as of 31 October, tags Orchard Dental Credit at − SGD 300.00: the clinic paid an invoice twice. At the clinic’s request, Priya opens the receipt and selects Refund unapplied.
Export. She exports October for Xero and downloads October’s Payment differences (CSV).

Common questions

Can I still invoice last month’s work after the month has ended? Yes. Give the invoice an earlier Invoice date; it cannot be later than today. Do it before you export the month.
Can I see what customers owed on the last day of the month? Yes. Set As of on Receivables ageing to that day; payments and credit notes dated after it are not taken off.
Why does an invoice the customer has paid still show a balance? The money may be on the account as unapplied, for example from a payment recorded without ticking the invoice. The invoice keeps its Balance due until you allocate the money to it with Allocate to invoices.