# Extend serial's warranty

By default, warranty is calculated automatically, based on fields on serials:

[![image.png](https://how-to-erp.dewesoft.com/uploads/images/gallery/2024-04/scaled-1680-/5GKimage.png)](https://how-to-erp.dewesoft.com/uploads/images/gallery/2024-04/5GKimage.png)

Conditions, that apply are (warranty enabled):

- if serial is not sold (this is necessary to show correct data in calibrator)
- if sold serials do not need calibrations (image below)
- if sold serials need calibration and are calibrated (**last calibration** is before current date and **next calibration** is after)
- if warranty is valid until the **warranty due** on serial number. This is generated from sales date to calculated date from product setting **warranty duration in months** (image below)

![image.png](https://how-to-erp.dewesoft.com/uploads/images/gallery/2024-04/scaled-1680-/JgZimage.png)

Warranty will turn off, when **warranty due** date passes or calibration was not done within **N** months from **next calibration** date (the N can be setup in ERP settings).

You can turn on warranty with **warranty** switch on serial's page. Be aware of automation explained in section below:

<p class="callout warning">Warranty will turn off every night, if settings are not correctly set up (e.g. **warranty due** or **next calibration** is missing based on conditions above)</p>

**Calibration** interval can be changed, if calibration is necessary more or less often. Zero mean 12 months.