> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gettap.co/llms.txt
> Use this file to discover all available pages before exploring further.
# Field mapping
> Decide which CRM field each captured answer lands in.
Field mapping connects a lead capture field to a CRM property. Get it right once and every lead flows correctly; get it wrong and data arrives in the wrong column, or silently doesn't arrive at all.
## How mapping works
Each mapping is a pair: a capture field's **name** on one side, a CRM field on the other.
```text theme={null}
Tap capture field CRM field
───────────────── ─────────
full-name ──────► First name + Last name
email ──────► Email
company-name ──────► Company
phone-mobile ──────► Mobile phone
note ──────► Description
```
The left-hand side is the field's `name`, never its `label`. This is why renaming a label is safe and changing a name is not — see [Lead capture forms](/en/leads/lead-capture-forms#labels-and-names).
## Built-in fields
Fields with reserved keys — `email`, `full-name`, `company-name`, `phone-mobile`, and the rest — map to your CRM's standard properties by default. Review the defaults, but you rarely need to change them.
`full-name` is collected as one field but most CRMs store first and last name separately. Tap splits on the first space: "Mary Jane Watson" becomes "Mary" / "Jane Watson". If your market has naming conventions this handles badly, collect the parts separately with custom fields.
## Custom fields
Custom capture fields have no reserved meaning, so Tap can't guess where they belong. Map each one by hand.
Tap can only map to fields that already exist. Create the custom property in HubSpot, Salesforce, or wherever, before you try to map to it.
Tap reads the available fields from your CRM when you open the mapping screen. If a property you just created isn't listed, reload the page.
Map text to text, dates to dates. A free-text answer pushed into a CRM dropdown field is rejected by the CRM, and the whole record can fail with it.
## Unmapped fields
A captured field with no mapping is **still stored in Tap** — you can see it on the lead and include it in an export. It simply doesn't reach the CRM.
This is worth knowing when you add a field mid-campaign: leads captured before you set up the mapping aren't lost, they just need a re-sync or an export.
## Updating existing contacts
When a lead matches a contact already in your CRM, Tap merges rather than overwrites. Empty incoming values don't erase existing data — a blank phone number in the capture form won't wipe the phone number your CRM already has.
Merge protects against blank overwrites, not against wrong ones. If a visitor mistypes their company name, that value **will** replace what's in the CRM. Merge means "don't erase with nothing", not "never change anything".
## Changing a mapping later
Mappings apply to leads captured **after** the change. Editing a mapping does not retroactively re-sync historical leads.
If you need to correct history, export the affected leads from Tap and import them into your CRM directly.
## Checklist before your first event
Walk the mapping screen top to bottom. An unmapped field is fine as long as it's a choice rather than an oversight.
If your CRM marks a property as required, every synced record must supply it. A required field with no mapping fails every single sync — and this is the most common cause of "nothing is arriving at all".
Capture a lead, open it in the CRM, and check each field individually. Five minutes here saves an event's worth of bad data.
Work through the troubleshooting guide.
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