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Understanding the Forecast

The forecast is Budget Forecaster's core feature: it projects your future account balance by combining your actual bank history with planned operations and budgets.

How It Works

graph LR
    subgraph Inputs
        HO[Bank history]
        PO[Planned operations]
        BU[Budgets]
        LK[Operation links]
    end

    subgraph Processing
        FA[Actualization]
        AF[Balance projection]
    end

    subgraph Output
        BE[Balance evolution]
        BF[Budget tracking]
        MS[Monthly summary]
    end

    HO --> FA
    PO --> FA
    BU --> FA
    LK --> FA
    FA --> AF
    AF --> BE
    AF --> BF
    AF --> MS

The forecast engine:

  1. Loads all planned operations and budgets
  2. Actualizes them using operation links (marks past iterations as done)
  3. Projects the balance forward day by day, adding expected income and expenses

Planned Operations

A planned operation represents a recurring or one-time expected transaction:

  • Salary on the 28th of each month: +2500 EUR
  • Rent on the 5th of each month: -800 EUR
  • Annual insurance on March 1st: -600 EUR

Each planned operation generates iterations - specific occurrences on their scheduled dates. For a monthly rent starting January, the iterations are Jan 5, Feb 5, Mar 5, etc.

Budgets

A budget represents a spending limit over a time period:

  • Groceries: 400 EUR per month
  • Leisure: 200 EUR per quarter

Unlike planned operations (single transactions), budgets represent aggregated spending. The budget amount is distributed evenly across each day of the period.

Links connect actual bank operations to their planned counterpart or budget. They tell the system "this bank transaction corresponds to this planned iteration."

Links can be:

  • Automatic: Created by heuristic matching (amount, date, category similarity)
  • Manual: Created by the user in the TUI (protected from recalculation)

See Operation Links for detailed usage.

Iteration Statuses

Each planned operation iteration has a status that affects the forecast:

stateDiagram-v2
    [*] --> Pending: iteration scheduled
    Pending --> Actualized: operation linked
    Pending --> Late: past due date, no link
    Late --> Postponed: tolerance exceeded
Status Meaning Effect on forecast
Pending Future iteration, not yet matched Included in projection
Actualized Linked to an actual bank operation Excluded (replaced by real amount)
Late Past due date with no matching operation Flagged, still included
Postponed Late beyond tolerance threshold May be rescheduled

What "Actualized" Means

When an iteration is actualized, the forecast replaces the planned amount with the actual transaction amount. For example:

  • Planned: Electricity -95 EUR on Jan 15
  • Actual: Bank shows -102 EUR on Jan 17
  • After linking: The forecast uses -102 EUR instead of -95 EUR

What "Late" Means

An iteration appears as LATE when its scheduled date has passed but no bank operation has been linked to it. This typically means:

  • The transaction hasn't arrived yet (delayed payment)
  • The bank statement hasn't been imported yet
  • The operation happened under a different description and wasn't matched

Late iterations remain in the forecast to keep the projection accurate.

Balance Evolution

The forecast computes your balance for every day in the report period:

  • Past dates: Uses actual bank operations (real transactions from your statements)
  • Future dates: Uses planned operations and budgets (projected from the actualized forecast)
  • Balance date: The pivot point - your last known actual balance
Past (actual)              Now              Future (projected)
──────────────────────────|──────────────────────────────
   Real bank operations   |   Planned operations + budgets
   Known amounts          |   Estimated amounts

The balance evolution chart is displayed in the Balance tab of the TUI. See Balance for usage details.

Budget Tracking

For each budget, the forecast tracks consumption. The Review tab provides a per-category view with these columns:

  • Planned: The full budget amount for the period
  • Actual: Sum of real bank operations linked to this category
  • Forecast: Projected spending for the current period based on links
  • Remaining: Forecast minus Actual — how much is left

See Monthly Review for the full tab documentation.

Daily Projection (Linear Decrease)

Budget spending is projected as a linear decrease over the period. For a monthly budget of 400 EUR in a 30-day month, the forecast assumes 400 / 30 = ~13.33 EUR spent per day.

When actual spending is known (via links), the remaining budget is spread over the remaining days. For example, if 150 EUR has been spent by the 15th:

  • Remaining budget: 400 - 150 = 250 EUR
  • Remaining days: 15
  • Daily projection: 250 / 15 = ~16.67 EUR per day

This gives a more realistic day-by-day balance curve than projecting the full amount on a single date.

Current Period Actualization

Budgets are considered fully consumed for the current period:

  • Spent less than the budget -> actualized = budget (e.g., spent 300 of 400 EUR -> actualized = 400 EUR)
  • Already exceeded the budget -> actualized = actual spending (e.g., spent 450 of 400 EUR -> actualized = 450 EUR)

In short: actualized = max(spent, budget).

Planned operations use the actual amount as soon as it's known:

  • If a planned expense of 150 EUR is linked to an actual operation of 100 EUR, the forecast projects 100 EUR (not 150 EUR)
  • If the iteration is not yet linked, the planned amount is used

Example

Monthly groceries budget: 400 EUR

Week Linked operations Remaining
1 Supermarket -80 EUR 320 EUR
2 Market -45 EUR 275 EUR
3 Supermarket -95 EUR 180 EUR
4 (forecast shows 180 EUR remaining)

If linked operations exceed the budget, the remaining amount goes negative (overspent).

Monthly Summary

The Review tab shows a per-category monthly summary with these columns:

Column Meaning
Planned Sum of planned operations and budgets for that month
Actual Sum of real bank operations for that month
Forecast Projected amounts for the current month, accounting for links
Remaining Forecast minus Actual — how much of each category is still expected

Categories are split into Forecasted (with planned counterparts) and Unforecasted (spending without a plan).

Excel Export

The forecast report can be exported to Excel from the Balance tab (press X). The export includes:

  • Balance evolution chart
  • Monthly summary by category (Actual / Planned / Forecast)
  • Budget statistics (total and monthly average per category)

Tips

  • Import bank statements regularly to keep the forecast accurate
  • Link operations manually when automatic matching fails (press L in the Operations tab)
  • Use budgets for variable spending categories (groceries, entertainment) and planned operations for fixed amounts (rent, salary)
  • Split operations when amounts change (e.g., salary increase) to preserve history while updating the forecast