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Rule-Based Projections

Rule-based projections automate your forecast using historical data and simple business logic. Instead of entering fixed amounts manually, you define rules that tell Cash Flow Frog what past data to use — and how to calculate future values.

Written by Ariel
Updated over 2 weeks ago

What You Can Do with Rule-Based Projections:

  • Use a rolling average (e.g. last 3 or 6 months)

  • Reuse past values (e.g. last month or same month last year)

  • Tie expenses to income (e.g. materials or commissions as a percentage of sales)

This keeps your forecast dynamic, consistent, and aligned with how your business actually performs — without constant manual updates.
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How It Works

Each rule-based projection is built from four components:

Lookback period — defines how far back from the projected date the data window starts.

For example, a lookback of 12 months means the window begins 12 months prior to each projected date.

Duration — defines the length of the data window.

For example, a lookback of 12 months with a duration of 3 months uses a 3-month window starting 12 months ago.

Filter dimensions — selects the relevant data by account, customer, vendor, or any dimension.

At least one filter is required.

Amount formula — determines how the value is calculated.

Choose between sum or average, then apply a percentage (e.g. 100% = same value, 110% = +10% growth, -XX% for the opposite amount).
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Creating a Rule-Based Projection

  1. Click Add Projection

  2. Toggle the Rule-based amount switch next to the amount field

  3. In the Amount Rule section:

    • Set the lookback period

    • Define the duration

    • Add at least one filter

    • Choose your formula (sum or average) and percentage

  4. Complete the remaining fields as you would for a regular projection
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Common Examples

Rolling average

Lookback: 6 months

Duration: 6 months

Filter: expense account

Formula: average

→ Automatically calculates each period based on recent activity.

Carry forward last month

Lookback: 1 month

Duration: 1 month

Formula: sum
→ Carries last month’s actual value forward as the projection.

Tie expenses based on percentage of revenue

Filter: income accounts

Formula: sum with percentage (minus. - 21%)

→ Projects costs like materials or commissions based on revenue.

Same month last year + growth

Lookback: 12 months

Duration: 1 month

Formula: sum at 110% (for 10% growth)

→ Ideal for seasonal businesses and annual planning.

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