Fix Zoho Books error: Email already exists for another contact person of this customer when changing VAT or Tax Rate

Zoho Books: "Email already exists for another contact person of this customer" when updating a customer's Tax Rate

When updating customers in Zoho Books, for example changing their Tax Rate to VAT Exempt, you may find that some records refuse to save and display the message "Email already exists for another contact person of this customer." This article explains why the message appears and how to complete the update without creating duplicate contacts.

Symptoms

  • You are working through a list of customers to change their Tax Rate (for example, to VAT Exempt [0%]).
  • Most customers update without any problem, but a small number show a red banner at the top of the Edit Customer screen and will not save.
  • The banner reads: "Email already exists for another contact person of this customer."

Cause

The tax change itself is not the problem. The error appears because the contact person you are entering already exists in Zoho Books with the same email address. Rather than working on the existing record, the edit is effectively trying to add that person a second time, and Zoho Books blocks the save to prevent a duplicate contact.

This is why only some customers in a bulk update are affected: the rest do not have a matching existing contact.

Before you start: one record or two?

Confirm how the business wants these customers set up. Does each company need a single VAT Exempt account, or do some need two separate entries (one with VAT and one without)? The steps below assume a single VAT Exempt account per company. If two entries are genuinely required, speak to your Zoho administrator or partner before making changes, as the setup will differ.

Resolution

  1. Leave the current screen without saving. Click Cancel so that no duplicate contact is created.
  2. Search for the existing contact. Go to Sales > Customers and search using the contact's email address (for example, name@company.com).
  3. Identify the linked company. The search results show which customer record the contact already belongs to. Open that customer and click Edit.
  4. Update the Tax Rate. On the Other Details tab, select the required Tax Rate (for example, VAT Exempt [0%]).
  5. Save. Click Save to apply the change.

Repeat these steps for each customer where the message appeared.

Note: If the search returns a different company from the one you expected, check with your team before changing anything. It may indicate the contact has been linked to the wrong customer, or that duplicate customer records exist.
Need help? As an experienced Zoho Partner, 1 Cloud Consultants can help you tidy up duplicate contacts and configure VAT and tax settings correctly in Zoho Books. Book a discovery call with 1 Cloud Consultants.