HubSpot Custom Workflow Guide: Pro-rata Calculation Based on Start and End Dates

Objective

The purpose of this action is to accurately distribute revenue or expenses that fluctuate based on a specific timeframe (Start Date to End Date) across months or days. By eliminating manual calculation errors, it enables real-time calculation and updates of the figures necessary for revenue recognition and budget management directly within HubSpot.

Use Cases

• Subscription Revenue Management: Prorating annual contract revenue into monthly segments to generate monthly revenue reports.
• First/Last Month Proration: Calculating the exact billing amount based on the number of days if a contract starts or ends in the middle of a month.
• Campaign & Ad Spend Allocation: Distributing the total budget of a multi-month marketing initiative across each month based on the active period.

Implementation Steps

1. Add and Connect the Action in Workflow

Click the "+" icon in the HubSpot workflow editor and select "Pro-rata Calculation" from the list of custom actions.

2. Select the Calculation Logic

Choose the calculation base from the dropdown menu according to your business requirements:

• Monthly Proration (MONTHLY): Divides by the actual "number of months." If starting mid-month, the first month is treated as "0.x months" to calculate the monthly equivalent.
• Daily Proration (DAILY): Divides equally by the "total number of days" in the period. It calculates a daily rate and allocates it based on the elapsed days in each month.

3. Specify Input Values (Amount and Period)

Map the source data from your HubSpot properties:

• Target Amount: The total contract value or budget (e.g., Deal "Amount").
• Start & End Date: Specify the date properties, such as the contract term.

4. Configure Rounding Details

Specify the precision of the calculation in the "Decimal Places" field:

• Set to 0: Rounds to the nearest whole number (common for JPY management).
• Set to 1–4: Use this for foreign currency management or when more detailed ratio calculations are required.

5. Output and Mapping of Calculation Results

Once the action completes, the following items are generated dynamically. Save these to your pre-created custom properties using the "Set property value" action:

• First Month Amount: The amount allocated to the first month.
• Mid-term Amount: The total amount for a "full month" excluding the start and end months.
• Final Month Amount: The amount allocated to the last month (the final value including any rounding adjustments).
• Number of Mid-term Periods: The number of full months between the start and end.
• Total Days: The total number of days from start to finish.

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