# Protected Fields: Keep External IDs From Matching | Dedupely > Stop Dedupely Intelligence from matching records whose external ID or another key field differs. Protect up to 5 fields and choose how blanks count. - URL: https://dedupe.ly/knowledge-base/protected-fields - Section: knowledge-base - Site index: https://dedupe.ly/llms.txt - Any page: append `.md` to its URL for this plain-text form --- Skip to content [New Dedupely Intelligence Now on every paid plan, monthly or yearly.](https://dedupe.ly/ai-deduplication) ## Protected Fields By [Gaby Salinas](https://www.linkedin.com/in/gbyslns) Updated November 11, 2026 Keep records from matching when a field that should never change is different. Protected fields keep two records from matching in Dedupely Intelligence when a certain field value differs between them. Use them for values that should never be overwritten by a merge, like external IDs from your ERP or billing system. You can protect up to 5 fields, and choose how blank values are treated. ### Before you start - **Dedupely Intelligence** on Contacts, Companies or Leads. See [Dedupely Intelligence](https://dedupe.ly/knowledge-base/dedupely-intelligence). - **A paid plan** to save your Protected fields. See [Dedupely Pricing](https://dedupe.ly/knowledge-base/pricing). - **Read & Modify on Merge rules and safety.** See [Roles and Permissions](https://dedupe.ly/knowledge-base/roles-and-permissions). ### When to use Protected fields - **External IDs:** two contacts with different ERP Customer Numbers are different customers, even if their names and emails look alike. - **Values that should never be overwritten:** like a billing account number or a contract ID. - **Separate entities with similar data:** two branches of the same company, each with its own ID. ### How to set up Protected fields - Go to **Duplicate Searches** and open **Dedupely Intelligence** under Contacts, Companies or Leads. - Click **Protected fields** at the top right. - Under **Never match values on differing fields**, click **Add a field** and choose the field. Add up to 5 fields. - Choose how blank values are treated: - **None can be blank:** records match only if every record has a value in the field, and the values are the same. - **At least one must not be blank:** records with a blank value can still match, as long as at least one record has a value. - **All can be blank:** blank values never keep records from matching. Only different values do. - Click **Save**. ### What happens next - **Records with different values in a Protected field stop matching** after the next background scan. - **Your Protected fields are saved**, so they apply to every scan. - **Nothing changes in your CRM.** Protected fields only change which records Dedupely Intelligence matches. ### Troubleshooting **A match I expected is missing.** One of your Protected fields might differ between the records. Check the field values, or remove the field from Protected fields. **I can't add another field.** You can protect up to 5 fields. **My Protected fields weren't saved.** They're saved on every paid plan, not in the free trial. See [Dedupely Pricing](https://dedupe.ly/knowledge-base/pricing). ### FAQs about Protected fields - **How many fields can I protect?** Up to 5. - **Do Protected fields work in my own Duplicate Searches?** No. They're for Dedupely Intelligence. In your own searches, use Match Settings and [Filters](https://dedupe.ly/knowledge-base/filters). - **Do Protected fields change my CRM?** No. They only change which records match. - **What's a good field to protect?** An external ID, like an ERP Customer Number or a billing account number. ### Next up [Manual Review: Set Aside Uncertain Matches to Review Later Send uncertain matches to a review queue so the right person can approve them.](https://dedupe.ly/knowledge-base/manual-review) ### Still stuck? Our team helps on every plan and during the free trial, by chat, email or Zoom. - Need help? [Talk to support](https://dedupe.ly/contact) - Questions about plans? [Book a Zoom with sales](https://meetings.dedupe.ly/meetings/gaby-salinas/kb-zoom-scheduler) - Reading this with a model? [Read this page as Markdown](https://dedupe.ly/knowledge-base/protected-fields.md) - Feeding it the whole site? [Read llms.txt](https://dedupe.ly/llms.txt) Behind the article ### Gaby Salinas Marketing Assistant at Dedupely Gaby Salinas came to CRM data from marketing and advertising, so she looks at duplicates from two sides: the match and merge logic behind them, and what they do to the people using the CRM, like the rep who calls a customer twice, the admin who gets blamed and the cleanup nobody wants to start. As Marketing Assistant at Dedupely, she follows how RevOps teams, end users, consultants and technical teams actually work with their data: the records they stop trusting, the workarounds they build and the moment they finally decide to clean up. What she finds shapes most of what Dedupely publishes. [Connect with Gaby on LinkedIn](https://www.linkedin.com/in/gbyslns) ### Get started for free 20 free trial merges and as much free support as you need to get your duplicates under control. [Try for free](https://v2.app.dedupe.ly/signup)[Talk to sales](https://meetings.dedupe.ly/meetings/gaby-salinas/talk-to-sales) [Or sign up with Google](https://v2.app.dedupe.ly/signup/google) Running CRM cleanup for clients? [See the Partner Program](https://dedupe.ly/become-a-partner)