IMPORTANT: We're sorry to say that as of 17/08/2020 we are no longer allowing new integrations with Xero. If you have integrated GES with Xero prior to this date, your integration will remain active for the foreseeable future, but we will not be allowing new integrations.

How it works

The way the integration works between the two software's is a one-way synchronisation. 

Any changes you make on GES will then sync with the accounting software, but changes you make on the accounting software will not sync over to GES. 

✅ GES ➡ sync ➡ Accounting Software

❌ GES ⬅ sync ⬅ Accounting Software

Any new customers/invoices will automatically and organically sync across to the accounting software as you do them - nice and easy! 😄

Unfortunately, your existing customers/invoices will not sync across until you edit them, as is this what triggers the new sync process to happen. 

Getting Started

The following guide will walk you through the integration with Xero and assumes you already have a working account with them. If you haven't done so already then it is advised you do this first before going ahead. It is also highly recommended that you add your bank account to your accounts package before enabling the integration. You will be asked to select the account where you want payments to go when you setup and authenticate GES with Xero.

The integration is a paid add-on that allows you to trial it for free for 14 days, once activated. You can cancel it at any time should you wish. After the initial 14 days, you will be charged for it.

GES can sync your customers, invoices, and payments.

Before enabling your integration, you should know that if any of your customers in Gas Engineer Software already exist on your accounting package then duplicates may be produced when syncing your existing data. Don't worry too much though, because you can very easily merge and unmerge duplicates in Xero at any time.

If you already have existing data on your accounting package then please contact us and we can speak about the options available to ensure that duplicate records are not produced.

Keep in mind that it is not currently possible to prevent the duplication of any existing invoices that may already exist on your accounting package. If some of your existing invoices in Gas Engineer Software have already been manually created under your accounting package, you could end up with duplicates in your accounts package in some circumstances.

If you have yet to add any data to your accounting package then the above does not apply to you.

Subscribe to the Integration

You will first need to subscribe to the integration by heading to the Gas Engineer Subscription Details. You will need to upgrade to the Growth Plan if you are not already. The growth plan includes the Accounts Integration.

Authenticate GES with Xero

  • Tick the two options for syncing both Customers and Invoices.

  • Click "Save Changes".

  • Click Authenticate.

  • Login to Xero (if not already).

  • Click Allow Access to give access to GES.

Choosing your Bank for Payments

The next step is to select which bank account you wish invoice payments from GES to be linked to. Select the appropriate bank from the drop down menu and click the Save button.

If you have not added your bank account yet, it is highly recommended that you do so now, before Authenticating. If there is no bank account, a dummy one will be created for payments. If payments get made to this account, you can only move them from it individually to another bank account at a later date. This is avoidable if you add your bank first.

After this step has been completed your GES account will then be linked with your accounting software. The status indicator on your Integration Settings page should now indicate that the link is now active.

The tick boxes will change the behavior of the integration. If, for example, the Sync customers option is checked then any new customers you create will automatically be synced to your accounting package.

Alternatively if the 'Sync invoices' option is checked, then both your customers and invoices will automatically be synced to your accounting package.


If any issues occur while the integration is active, they will be logged on
your integration settings page. Typically these errors will be thrown back
by the service itself and not by Gas Engineer Software, and unfortunately at times these
messages can be vague.

Gas Engineer Software will often provide you links to the record in question
that was being synced when the fault occurred but the below will walk you
through what each message might possibly mean.

Common Error Messages

"Invoice not of valid status for modification."

This is indicating that the invoice under Xero has been modified - when this occurs, Gas Engineer Software is unable to modify it any further through Xero's API and is in essence locked out.

Unfortunately once this has occurred the only way forward is to modify them independently from one another.

"Another contact has this contact number. Please enter a different contact number."

This means that Gas Engineer Software attempted to sync a customer to Xero, but a customer with the same Unique ID number (Contact Number) already exists under Xero.

Xero requires that each contact has their own unique ID number.

This usually is the case when a contact has been archived in Xero, thus the GES contact can no longer sync to it. To fix this, look in archived contacts in Xero for the same customer name, and restore that contact.

Please see below for further information on dealing with duplicate contacts under Xero.

"Account code '200' has been archived, or has been deleted. Each line item must reference a valid account."

You must make the account code 200 available for GES Sales in order to sync.

  1. First go into your ‘Settings’ and then ‘General Settings’

  2. From there go into ‘Chart of Accounts’

  3. You’ll see a few tabs just below the buttons listed, such as ‘All Accounts’, ‘Assets’ and at the end ‘Archive’

  4. If you click on the ‘Archive’ option, you should see an entry with a code of ‘200’ which will need to be restored on the account. This is a default account that Xero requires to exist - even if it is not used.

Click on the checkbox beside it and then click on ‘Restore’.

Once you’ve done this, you’ll be able to go back into your ‘Integration Settings’ within Gas Engineer Software and try syncing again. If the account does not exist, you can create it.

"Organisation is not subscribed to currency EUR."

Within Gas Engineer Software, you're likely using Pounds as the selected currency but under your Xero organisation you are using a different form of currency.

You will need to match this setting between Gas Engineer Software and Xero in order to rectify the problem.

"The status 'ARCHIVED' is not valid for contacts."

The customer has been archived under Xero. The solution is to restore that archived contact in Xero.

"This document cannot be edited as it has a payment or credit note allocated to it."

The invoice in question has already been marked as paid in Xero, in which case Xero will lock Gas Engineer Software out from making any further changes - in this case you will need to make your changes in Xero. Just make sure the invoices match and are correct, and ignore the error from then on.

"You have reached the limit of invoices you can approve."

Your Xero account won't let you add any more approved invoices, either because you're on the "Starter" plan or you are currently using the trial version of the software.

Duplicate Contacts when Syncing

If you find that you have created a duplicate contact in the syncing process, you can merge the two contacts together in Xero, and keep the existing invoices of both under one. The key is to merge the existing Xero contact to the newly synced/created GES contact. This is because invoices for this contact will be linked to the GES version of this contact. You can always undo this process as well.

Frequently Asked Questions

How do I disconnect from Xero and stop the integration?

You open the Subscription Settings, and remove it from there by clicking on the "Manage Subscription" button.

How can I sync my historical or older invoices?

The only way to sync older records is to open the individually on the web portal, and then quickly edit and re-issue the invoice. This will update the invoices timestamp, and sync it over immediately. This is the same for contacts/customers. Any edits to a contact not already in Xero, will sync that contact over immediately.

Syncing occurs usually straight away, but there can be delays depending on connection congestion etc. The sync is automatic - if you issue an invoice, it will automatically sync the invoice and the customer. There are only 2 settings for the synchronisation once you have setup and authenticated; sync customers, and sync invoices. You must have sync customers enabled before invoices can be synced as well.

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