# Time Segments

## Overview

**Time Segments** allow a [**Variable** ](https://help.taglo.io/variables)to calculate its values differently depending on the period of the [**Model**](https://help.taglo.io/models).

<figure><img src="https://2847533834-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FVy65sax6FVoNo2UTlJ0x%2Fuploads%2FLmaqMGOMeMMJfQIdgw98%2Fimage.png?alt=media&#x26;token=bd38ac82-2bd9-42e1-bc0e-ef1793f7c5c5" alt="Shows the preview panel of a Variable with two Time Segments" width="563"><figcaption><p>Example Variable with two Time Segments</p></figcaption></figure>

For instance, in the example above, the `Monthly price per member` Variable calculates its value using an inflation [**Calculation**](https://help.taglo.io/calculations): `Monthly price per member [-1] * (1 + Price inflation)`.

This Variable references the previous period's value of itself (indicated by the `[-1]` part of the Calculation). At the start of the Model, we need to tell the Variable what that value should be, as there are no previous periods to obtain the value from.

We do this by creating a new Time Segment for the first period of the Model, which will act as an `Assumption` segment, which we can link to the inputs of the Model. The second Time Segment is an `Auto` segment, meaning it performs the default Calculation of the Variable.

The rest of this section explains the various ways of creating and manipulating Time Segments, and the implications of using them.