> ## Documentation Index
> Fetch the complete documentation index at: https://zenskar.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Line item: billing

## Line item: billing

This page explains when and how often Zenskar invoices a line item.

### Map of concepts

| Concept | Details |
| - | - |
| [Billing version](#billing-when-zenskar-invoices) | Each billing version has a billing cadence and a payment timing. |
| [Billing and pricing](#billing-and-pricing) | The billing has to fit the pricing of the line item. |

### Related modules

The billing of a line item uses the following modules:

| Module | Details |
| - | - |
| [Products](/docs/20260301/product-modules/products/concepts/products) | The pricing preset of a line item decides which billing fits. You create pricing presets in that module. |
| [Contracts](/docs/20260301/product-modules/contracts/concepts/contracts) | Billing belongs to the line items of a contract. |

## Billing: when Zenskar invoices

A **billing version** is the [version](/docs/20260301/product-modules/contracts/glossary#version) of the billing of a [line item](/docs/20260301/product-modules/contracts/glossary#line-item). Each billing version has a billing cadence and a payment timing. A line item starts with the billing of its [pricing preset](/docs/20260301/product-modules/products/glossary#pricing-preset). If the pricing preset has no billing setting, the line item starts with monthly billing, prepaid.

The **billing cadence** is how often Zenskar invoices a line item, such as monthly. The billing cadence can be monthly, quarterly, semi-annual, annual, or a custom length.

A **billing period** is one period of the billing cadence, such as one month.

**Payment timing** is whether Zenskar invoices a line item at the start of each billing period or at the end:

| Payment timing | When Zenskar invoices |
| - | - |
| Prepaid | At the start of each billing period, for that period. This is the default. |
| Postpaid | At the end of each billing period, for that period. |

For example, a seat line item with monthly prepaid billing is invoiced on 1 March for March. An API line item with monthly postpaid billing is invoiced at the end of March for the calls made in March.

## Billing and pricing

The billing has to fit the pricing of the line item:

* A line item with [metered usage](/docs/20260301/product-modules/products/glossary#metered-usage) that uses the [on-demand quantity strategy](/docs/20260301/product-modules/products/glossary#on-demand-quantity-strategy) cannot be prepaid, because Zenskar cannot know the usage before the billing period.
* For a [period-of-time product](/docs/20260301/product-modules/products/glossary#period-of-time-product-type), the [pricing period](/docs/20260301/product-modules/products/glossary#pricing-period) and the billing cadence must align: one must be a whole multiple of the other. For example, a monthly price can be billed quarterly. Each quarterly invoice then covers three pricing periods:

  ```mermaid theme={null}
  gantt
    title A monthly price billed quarterly
    dateFormat YYYY-MM-DD
    axisFormat %b
    section Pricing periods
    Jan                      :2027-01-01, 2027-01-31
    Feb                      :2027-02-01, 2027-02-28
    Mar                      :2027-03-01, 2027-03-31
    Apr                      :2027-04-01, 2027-04-30
    May                      :2027-05-01, 2027-05-31
    Jun                      :2027-06-01, 2027-06-30
    section Billing periods
    Invoice for Q1           :2027-01-01, 2027-03-31
    Invoice for Q2           :2027-04-01, 2027-06-30
  ```
* For a [point-in-time product](/docs/20260301/product-modules/products/glossary#point-in-time-product-type) with the [volume](/docs/20260301/product-modules/products/glossary#volume-pricing-model) or [tiered](/docs/20260301/product-modules/products/glossary#tiered-pricing-model) pricing model, the [tier-reset period](/docs/20260301/product-modules/products/glossary#tier-reset-period) must also align with the billing cadence.

Within each [pricing version](/docs/20260301/product-modules/contracts/glossary#pricing-version), the billing versions must cover all the dates, or none. Without billing versions, the line item uses the billing of its pricing preset.


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