A customer's remittance pays twelve invoices. The deposit matches the remittance to the cent, the batch reconciles in Xero, and five of the twelve invoices are still sitting in aged receivables with $0.01 owing. Nobody short-paid anything on purpose. Your invoices worked GST out one way and the customer's payment system worked it out another, and the difference landed on your ledger a cent at a time.
Why GST rounding leaves a cent open
GST has to be rounded to the cent somewhere. Xero works it out on each line of an invoice, rounds each line to the cent, and then adds the lines up. Many purchasing and accounts payable systems work it out once, on the total. The ATO names more than one rounding rule for an invoice with several items, and its guidance on tax invoices says you and your customers don't need to use the same one. So neither side is wrong, and the two figures can still differ by a cent.
It shows up most with customers who raise a purchase order for the invoice total, pay from an accounts payable system that recalculates tax, or key your invoice into their own ledger rather than importing it. Large organisations and government buyers are the usual sources, because their systems apply one rounding rule to every supplier. Xero calculates GST the same way in New Zealand, so the same cent turns up there too.
GST isn't the only source. Anything that multiplies and then rounds can do the same thing: hours times an hourly rate, a quantity times a unit price, or a funding claim calculated in one system and paid from another. If the payer's calculation and your invoice round at different steps, the cent appears whatever tax is involved.
One cent on one invoice is nothing. One cent on a third of the invoices from your biggest customer, every week, is a list of tiny balances that never clears itself.
Is it rounding or a short payment?
Before you clear anything, make sure it really is rounding. The pattern is distinctive.
- The difference is a cent or two per invoice. GST rounding can't produce more than a cent or so per line, so an invoice with a handful of lines can only be out by a few cents.
- It repeats with the same customer. Their system rounds the same way every time, so the same customer is short on many invoices and the rest of your customers are not.
- It goes both ways. Depending on the amounts, total-based rounding sometimes lands a cent above your invoice rather than below it.
- The remittance shows the lower figure. The customer believes they paid in full, because by their numbers they did.
A difference of several dollars, or one that appears on a single invoice for a reason the remittance explains, is something else: a deduction, a dispute or a mistake. Those need a conversation with the customer rather than a write-off, and our guide to remittance deductions in Xero covers them.
Clearing the cent in Xero by hand
There are two common ways to close the balance, and which one fits depends on whether you've already recorded the payment.
A credit note, after the payment. If the payment is already recorded for what the customer paid, the invoice has a cent outstanding. Raise a sales credit note to the same customer for that amount, coded to the account you use for rounding, and allocate it to the invoice. The invoice closes and the payment is untouched, so anything already reconciled stays reconciled. When several invoices from one customer are short, one credit note can be allocated across all of them, which is far quicker than one per invoice.
A minor adjustment, at reconciliation. If you haven't recorded the payment yet, you can pay each invoice in full and let the bank reconciliation absorb the difference. On the statement line, use Find and match, select the payments, and under Adjustments choose Minor adjustment for the small difference between the bank line and the payments. Xero posts it to its own Rounding account. That works neatly for one payment against one invoice. For a batch it means recording each invoice at its full amount, so the batch no longer equals the deposit, and the adjustment has to be added at reconciliation every time.
To find the ones already sitting there, open your awaiting payment invoices and sort by the amount due, or run an aged receivables report and look for balances of a few cents. They tend to cluster under a handful of customers, which tells you where the next ones will come from.
For credit notes, pick one account and use it every time. Xero's own Rounding account accepts a credit note line, so credit notes and minor adjustments can land in the same place. A year of entries in one place shows which customers' systems cause it, which is useful when you raise it with them.
When the customer pays a cent too much
Total-based rounding can just as easily land a cent above your invoice. Here the invoice can't be paid for more than it's worth, so record the payment for the invoice amount and the bank line ends up a cent higher than the payments. Clear that at reconciliation with a minor adjustment, which Xero posts to its Rounding account. There's no need to refund a cent or carry it as a credit on the customer's account.
Setting a threshold for small differences
The decision that saves the most time is made once, with your accountant, rather than invoice by invoice. Agree three things.
- A limit per invoice. Below it, a difference is written off without a query. A few cents covers GST rounding; anything larger deserves a look, since genuine short payments are usually dollars rather than cents.
- An account. The account every write-off goes to, so they're easy to find and total at year end.
- How GST is treated. Whether the write-off carries GST is a question for your accountant. On a cent, the GST involved is a fraction of a cent, so the answer is usually about consistency rather than money.
Write the policy down. When a new person takes over receivables, a written threshold stops them either chasing customers for a cent or, just as bad, quietly writing off dollars because the last person did.
Reducing it at the source
A cent per invoice can be cleared, but it's better if it never appears. A few things help.
- Ask the customer. A short note to their accounts payable team, with one invoice showing the difference, sometimes leads them to pay your invoice total rather than their own calculation.
- Match their purchase order. Xero doesn't let you change the GST it calculates on a line, but it does let you add a line coded to a rounding account. For a customer whose order total is always a cent off, a small rounding line brings your invoice to their figure.
- Consolidate lines. Fewer lines means fewer rounding steps. Where the detail isn't needed on the invoice, one line per order can stop the difference appearing at all.
None of these will fix every payer, because a large customer's system won't change for one supplier. That's where an agreed threshold and a routine write-off earn their keep.
Where RemitClear fits
RemitClear reads the remittance, whether it's a PDF, a spreadsheet or the body of an email, and matches each line against your open invoices in Xero. Matching handles exact, partial, and prefix-based invoice numbers. You set a posting tolerance, and a difference within it doesn't hold a remittance back: it still counts as a perfect match, so with automatic posting on it posts by itself, for what the customer paid, with the remittance attached. The payment still equals the deposit, so it reconciles as usual.
Switch on Write off differences within the tolerance and RemitClear closes those cents too, to Xero's Rounding account unless you pick another. After the payment posts, every invoice left short by no more than your tolerance is closed with a credit note to that account, one per customer, allocated to the invoices it covers and raised without GST. The batch still equals the deposit, so bank reconciliation doesn't change, and the credit note sits with the payment's Xero links. A difference above the tolerance, or an invoice the customer has only part-paid, is never written off; it waits for a person to look at it. See how remittance matching works in Xero.
