> For the complete documentation index, see [llms.txt](https://help.modelreef.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.modelreef.io/syntax/timing-syntax/seasonality-inputs.md).

# Seasonality Inputs

This article explains **Seasonality inputs** in the Timing modal.

You will learn:

* What seasonality controls.
* How to enter seasonal patterns.
* How seasonality interacts with frequency and delays.

Seasonality lets you skew accruals towards some periods and away from others while keeping annual or total values anchored.

{% stepper %}
{% step %}

### What seasonality does

Seasonality defines relative weights for periods within a cycle, for example:

* Higher revenue in December and lower in January.
* Higher volumes in summer months.
* Lower demand in holiday weeks.

The timing engine uses these weights to reallocate accruals across periods without changing the total over the cycle.
{% endstep %}

{% step %}

### Entering seasonality patterns

You can configure seasonality by:

* Entering multipliers for each period of a cycle (for example 12 values for monthly seasonality across a year).
* Using a preset pattern where available.
* Importing a seasonal index series from external data.

Values are typically relative, such as 0.8, 1.0, 1.2, representing below average, average and above average periods.
{% endstep %}

{% step %}

### How seasonality interacts with base frequency

The base frequency and schedule determine **when** accruals can happen. Seasonality then adjusts **how much** weight each eligible period receives, for example:

* A yearly total is allocated more heavily to some months than others.
* A weekly schedule has some weeks scaled up or down based on the seasonal pattern.

Seasonality does not change total volume over the defined seasonal cycle unless you explicitly scale it.
{% endstep %}

{% step %}

### Seasonality and cash timing

Seasonality affects accrual timing. Cash timing is still governed by delays and payment terms:

* Seasonal peaks in accrual will create corresponding peaks in receivables or payables when delays are present.
* Cashflow peaks will lag accrual peaks by the specified delays.

Check both P\&L and cash outputs when adjusting seasonality.
{% endstep %}

{% step %}

### Validating seasonal settings

To validate seasonality inputs:

* Use the Timing preview to see the shaped pattern over time.
* Compare seasonal results to historical data where available.
* Ensure the pattern makes sense for the business (for example matching known busy seasons).

Adjust carefully to avoid overfitting or unrealistic profiles.
{% endstep %}
{% endstepper %}

***

## Related articles

* [Entering Seasonality](/syntax/how-input-fields-work/entering-seasonality.md)
* [Frequency Inputs](/syntax/timing-syntax/frequency-inputs.md)
* [Categories](/help/building-your-model/categories.md)
* [Combine Multiple External Data Sources](/how-tos/data-workflows-and-automation/combine-multiple-external-data-sources.md)