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Action Tags Autofill

Autofill Action Tags

Article ID RC-AT-06 — Autofill Action Tags
Domain Action Tags
Applies To All REDCap project types; requires Project Design and Setup rights
Prerequisite RC-AT-01 — Action Tags: Overview
Version 1.0
Last Updated 2026
Author See KB-SOURCE-ATTESTATION.md
Related Topics RC-AT-01 — Action Tags: Overview; RC-AT-05 — Free Text Action Tags; RC-LONG-01 — Longitudinal Project Setup; RC-FD-02 — Online Designer

1. Overview

This article covers action tags that automatically populate field values when a form or survey is first loaded: the @NOW and @TODAY families, device-based tags, user-based tags, and the flexible @DEFAULT and @SETVALUE tags.

Autofill tags only populate values on page load if the field is currently empty. Existing values are never overwritten (except by @SETVALUE, which always overwrites).

2. Date & Time Autofill Tags

These tags fill text boxes with date and/or time values. All have no parameters.

Tag Fills with Notes
@NOW Current date/time from user's device Use for date-time fields
@NOW-SERVER Current date/time from REDCap server Better for multi-timezone scenarios
@NOW-UTC Current date/time in UTC Consistent reference
@TODAY Current date from user's device Use for date-only fields
@TODAY-SERVER Current date from REDCap server For multi-timezone scenarios
@TODAY-UTC Current date in UTC Consistent reference

Applies to: Text box and notes box with corresponding date/time validation.

Use case: Timestamp fields, survey completion dates, or any field where the current date/time is the expected value.

3. Device & User Autofill Tags

Tag Fills with Notes
@LONGITUDE Device longitude Subject to privacy settings; may be blank or inaccurate
@LATITUDE Device latitude Subject to privacy settings; may be blank or inaccurate
@USERNAME Current REDCap username Fills with "survey-participant" when accessed via survey
@CONSENT-VERSION E-consent version number Only applies to surveys with e-consent framework enabled

Applies to: Text box (varies by tag).

Note on location accuracy: Device location depends on privacy settings. Many devices allow users to disable location services or reduce accuracy. VPNs can also return incorrect values. Treat location data as approximate.

4. @DEFAULT — Pre-fill on First Load

Pre-fills a field only when the form has never had data entered (status is "grey/incomplete"). Once the respondent saves data, @DEFAULT no longer applies.

Applies to: Text box, notes box, radio button, dropdown, checkbox, slider fields.

Use case: Setting expected default values that respondents may override.

4.1 Static Values in Text/Notes Boxes

@DEFAULT='Green'

4.2 Raw Values in Radio/Dropdown/Checkbox

@DEFAULT='2'

For multiple selections in checkboxes:

@DEFAULT='1,2'

4.3 Dynamic Values — Piping

Pre-fill with a value from another field in the same record:

@DEFAULT='[email]'

4.4 Dynamic Values — Smart Variables

Pre-fill with a system value:

@DEFAULT='[user-fullname]'

4.5 Longitudinal Projects

Carry forward a value from the previous event:

@DEFAULT='[previous-event-name][rx1]'

Pre-fills the field with the value of rx1 from the most recent prior event. Requires understanding of longitudinal projects (see RC-LONG-01 — Longitudinal Project Setup).

5. @SETVALUE — Pre-fill on Every Load

Like @DEFAULT, but fills the field every time the form is loaded, overwriting any existing value. Use when the field should always reflect the most current value on load.

Syntax: Identical to @DEFAULT.

Use case: Tracking the last user to touch a form, or always pulling the most recent data from another field.

Backward compatibility note: Older REDCap versions used @PREFILL (which still works but is deprecated).

6. Combining Autofill Tags with Visibility Tags

Autofill tags are often combined with @HIDDEN or @READONLY variants:

@NOW @HIDDEN

Creates a hidden timestamp recording when a form was first loaded.

@USERNAME @READONLY

Pre-populates with the current user's username and locks it to prevent manual edits.

7. Common Questions

Q: When should I use @DEFAULT versus @SETVALUE?

A: Use @DEFAULT when you expect the field to be filled once and then potentially updated by the respondent. Use @SETVALUE when the field should always reflect a freshly computed or looked-up value on every load.

Q: Can I use piped variables and smart variables in @DEFAULT/@SETVALUE?

A: Yes. Any valid piped field reference (e.g., [email]) or smart variable (e.g., [user-fullname]) can be used as the parameter.

Q: What is the difference between @NOW and @TODAY?

A: @NOW fills both date and time. @TODAY fills date only. If your field has a date-only validation, use @TODAY.

Q: Do autofill tags work during data import?

A: No. These tags only execute when a form is loaded in a browser. They do not run during API uploads or Data Import Tool uploads.

8. Common Mistakes

Using @SETVALUE on fields where respondents expect data to persist. Unlike @DEFAULT, @SETVALUE replaces the value every time the form loads. Avoid on fields where users expect their previous entries to remain.

Using @NOW on a date-only field. If the field has a date-only validation, use @TODAY instead. @NOW on a date-only field will still populate the date, but the time component is discarded.

Applying @TODAY or @NOW to a field with no date validation. Both tags will autofill any text field regardless of whether date or datetime validation is set. If the field has no validation, REDCap fills it with a date or datetime string on first load — but does not enforce the format on save. Users can overwrite the autofilled value with free text, and REDCap will accept it. Over time this produces inconsistently formatted data in what was intended to be a timestamp field. For reliable timestamp capture, always set the matching validation type: date_mdy (or date_ymd, date_dmy) for @TODAY fields, and datetime_ymd (or another datetime variant) for @NOW fields. The validation enforces format consistency on every entry, not only the autofilled ones. If you need a reliable date anchor for calculations but want to keep a visible field without format restrictions, see the hidden anchor field pattern in RC-FD-10 — Advanced Workflow Patterns: Multi-Stage Review and Operational Processing.

Expecting autofill tags to populate during data import. These tags run only when a form is loaded in the browser.