Sync subitem dates with the parent (per-task Numbers offset)
TL;DR: When the parent's date changes, every subitem's date recalculates to parent + its own per-task offset (a Numbers column on each subitem). The #5 most-used Subitem Automation — used by 6% of all accounts.
What this does
Recipe: "When item's date changes, change its subitems date to the same date with + offset by this number column of days/weeks/months."
Each subitem has a Numbers column where you store its individual offset (e.g. Design = 3, QA = 14, Launch = 21). When the parent's date changes, every subitem's date becomes parent date + that subitem's offset. One recipe replaces what would otherwise be many "shift by X days" automations.
Example: parent Launch Date moves from Jan 1 → Jan 15. Subitem Design (offset 3) auto-becomes Jan 18. Subitem QA (offset 14) becomes Jan 29. Subitem Launch (offset 21) becomes Feb 5.
When to use it
- Project templates with varied per-task timing — different tasks have different lead times
- You want to change one project date and have every subitem date recalculate accordingly
- Avoiding the "one automation per offset" trap — this is the scaleable version
- Negative offsets work too — for "task ends N days BEFORE the parent date" patterns (event prep, deadlines)
This is the on-change variant. For the on-creation version (set initial dates from the parent + Numbers offset), see Set per-task due dates using a Numbers column . Most teams use both — one to set initial dates, this one to keep them synced when the parent moves.
Before you start
- A Date column on the parent item (the trigger)
- A Date column on the subitem (the date that adjusts)
- A Numbers column on the subitem (name it Offset)
- Each subitem must have its offset value filled in for the recipe to work on it
Set it up (3 minutes)
Install and Search for the App
1. Click the Integrate button at the top right of your workspace.
2. Type Subitems Automations into the search bar. Click the Subitem - All automations app tile.
3. Type "+ offset" in the search field to filter the available templates.Click the template titled When item's date changes, change its subitems' date to the same date + offset by this number column.
Configure the Automation Parameters
4. Click the first date placeholder and select the parent item's Date column from the dropdown. (This also works on Timeline columns)
5. Click the second date placeholder and select the subitem's Date column from the dropdown. (This also works on Timeline columns)
This automation works with both standard date columns and timeline columns. You can use a timeline for the parent item and a due date for the subitem, or any other combination.
6. Click number column and select your subitems' Offset column.
7. Click the time interval placeholder and choose the preferred offset scale.
Days
Calculates the offset using standard calendar days, including weekends.
Business Days
Calculates the offset using only working days, automatically skipping weekends.
Weeks
Shifts the date by complete 7-day increments.
Months
Shifts the date by full calendar months.
10. Click Create Automation to finalize and save your rule.
Success: A webhook is automatically generated in the background when the automation is saved. This securely bridges monday.com 's due date updates with the automation app without requiring manual setup.
Test the Workflow
To verify the automation, input numerical values into the subitem offset fields to represent the days prior to (negative) or following (positive) the parent item's due date.
10. Enter -8 in the Offset field for your first subitem.
11. Enter -3 in the Offset field for your second subitem.
12. Type 5 in the Offset field for your third subitem.
13. Enter 10 in the Offset field for your fourth subitem.
Info: You can automatically populate the numbers in the Offset column. You don't have to manually type it in. If you have a native automation for creating new subitems (When status changes to something, create subitem), you can map the value of the Offset value from there — so every time a new subitem is created, it already has an offset value.
14. Change the parent item's due date to trigger the calculation.
15. The subitem due dates will immediately recalculate to align with the new parent date and their respective offsets.
Q: Can I use timeline columns instead of date columns?
A: Yes, this automation works with both Date and Timeline columns. You can use timeline for the parent item and due date for the subitem, or mix and match as needed.
Q: Why was a webhook automatically created after I saved the automation?
A: The webhook is automatically generated by the app to allow
to send information when due dates change. No action or configuration is required on your part.
Subitem
A secondary task nested under a primary parent item in monday.com , used to break down work into smaller steps.
Webhook
An automated mechanism that sends data from
to the Subitem Automations app whenever a specified event (like a date change) occurs. Webhooks do NOT consume your action credits on Subitem Automations.
Offset
A specific number of days, weeks, or months used to calculate a new date relative to a base date.
Common gotchas
- Empty Numbers cells = no shift. A subitem with no value in the Numbers column is ignored when the parent moves. Fill them in or expect those subitems to stay put.
- Numbers column type only. Text columns containing numbers won't work — must be the actual Numbers column type.
- Updates fire on every parent date change. If the parent date is volatile (changes often), every subitem recalculates each time. That's the design — but be aware on large boards.
- Pair with the on-creation variant. Use Set per-task due dates using a Numbers column on creation, this one for ongoing sync.
- Combine with weekend → workday. If your offsets land subitems on weekends, layer Auto-shift weekend dates to a workday on top to keep dates clean.
Next up
Related
- Date & timeline automations (parent landing)
- Sync all subitem dates with the parent (simpler — all subitems shift by the SAME amount)
- Date + offset — full reference
Still stuck?