How Sumext Maps Xero Tax Codes
Incorrect tax codes in Xero can cause GST reporting errors and BAS miscalculations. Sumext is designed to get this right automatically.
How Tax Code Mapping Works
When you connect Xero, Sumext syncs all your tax rates directly from your Xero organisation. These appear as options in the Review screen Tax Code dropdown.
When you approve a bill with a specific tax code, Sumext saves that as a vendor rule. Future invoices from the same vendor use the same tax code automatically.
Common Xero Tax Codes
GST on Expenses (10%)
Standard GST on purchases. Used when the supplier charges GST and the extracted tax amount is 10% of subtotal.
BAS Excluded
Transactions not reported on BAS, such as bank fees, wages, tax payments, or PAYG withholding.
GST Free Expenses (0%)
GST-free purchases such as fresh food, some medical items, or exports.
No GST
Simplified zero-rate fallback when no tax is detected and no vendor rule exists.
How Sumext Decides Which Code
- User-approved rule exists? Use that vendor's saved tax code.
- Tax amount on invoice? Calculate percentage of subtotal, match to nearest Xero tax rate, and apply that code.
- Zero tax detected? Find your organisation's zero-rate equivalent in Xero and apply it.
- No match found? Leave tax code blank for manual selection and flag for review.
Checking Your Tax Codes in Sumext
Go to Integrations → Xero → Tax Rates. You will see all tax rates synced from Xero with tax name, rate percentage, and type. Click Sync Tax Rates if they are out of date.
Manual Override
In the Review screen, the Tax Code field is always editable. If you change a suggested code before submitting, that change is saved as a new vendor rule for future invoices.
Frequently Asked Questions
Why does Sumext sometimes suggest BAS Excluded?
If Sumext cannot match the extracted tax to any rate in your Xero organisation, it may fall back to BAS Excluded. Sumext now dynamically matches against your actual Xero tax rates rather than using hardcoded defaults.
My tax codes changed in Xero. How do I update Sumext?
Go to Integrations -> Xero -> Sync Tax Rates, or disconnect and reconnect Xero to trigger a full sync.
Can I see which tax code was used on a past bill?
Yes. Open any submitted document in Costs -> Documents. The tax code applied is shown in the bill details.