This guide explains how to use the third-party app "Custom Workflow Starter" within HubSpot to add or subtract days from a specific date property in a workflow and save the result to another property.


The goal is to automate flexible date calculations within workflows—something that can be difficult with HubSpot's standard features. By calculating dates such as "X days later" or "X days ago" based on existing date properties and storing the values in fields, you can improve the accuracy of task and deadline management.
This action can be utilized in the following scenarios:
In the workflow editor, click the "+" button to add an action. Select "Custom Workflow Starter" from the app list, then click "Date Add/Subtract Action v2" from the action list.
Once the settings screen opens, select the date property to serve as the basis for the calculation.
Next, enter the numerical value for how many days you want to shift the date.
4).-4).Click "Save" when finished.To reflect the calculated date in a contact property, add the next action.
In the value setting for the update, dynamically reference the result calculated earlier.
Activate the workflow or perform a test run. Check the activity log of the target record to confirm that "Date Add/Subtract Action v2" succeeded and that the subsequent "Edit record" action has written the correct date (e.g., original date + 4 days) to the property.
The "Calculation" action alone does not save the data. You must combine it with an "Edit record" action. The app action (Date Add/Subtract Action v2) only functions to "calculate a new date and hold it temporarily." To actually reflect this result in a HubSpot property (e.g., Next Contact Date), you must add a standard HubSpot "Edit record" action immediately after the calculation step. In that step, you need to map the "Calculated Date" output to your target property. Please review steps 4 and 5 of the setup guide.
Yes, you can. Simply enter a negative number in the input field. There is no separate switch for addition or subtraction. You control this via the "Add/Subtract" field: For Future Dates (Add): Enter a positive integer (e.g., 30). For Past Dates (Subtract): Enter a negative integer (e.g., -30). This allows you to create trigger dates, such as "30 days before the contract end date."
Yes, this is possible. It is useful for scenarios like extending deadlines. It is perfectly fine to set the "Source Property" (from Step 2) and the "Target Property" (in Step 4) to be the same field. For example, you can read a "Deadline Date" property, add 7 to it, and save it back to the "Deadline Date" property. This effectively automates the process of "extending the current deadline by one week."
We can customize this sample to match your specific business requirements.
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