# BT-134 Invoice line period start date

The date when the period for the invoice line starts.

## Quick answer

> **Line items**: The goods or services on each invoice line, including quantities, prices, and VAT.

- [Validate XML](/en/xrechnung-validator?source=resource&bt=BT-134)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&bt=BT-134)

## In plain language

The date when the period for the invoice line starts.

The date when the period for the invoice line starts.

Used for services or subscriptions with specific billing periods.

## What you usually enter here

ISO 8601 date format (YYYY-MM-DD)

Typical valid values include: 2024-01-01, 2024-03-15, 2024-12-31

Optional according to EN 16931-1.

## What goes wrong often

Avoid values like: 01.01.2024, 2024/01/01, 2024-13-01

## Examples in context

Used for services or subscriptions with specific billing periods.

Optional according to EN 16931-1.

## Valid Examples

- 2024-01-01
- 2024-03-15
- 2024-12-31

## Invalid Examples

- 01.01.2024
- 2024/01/01
- 2024-13-01

## Related Fields

Used for services or subscriptions with specific billing periods.

- [BT-126 Invoice line identifier](/resources/xrechnung/bt-126-invoice-line-identifier)
- [BT-135 Invoice line period end date](/resources/xrechnung/bt-135-invoice-line-period-end-date)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-134

### Data Type:
date

### Cardinality:
0..1

### Requirement:
Optional

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:InvoiceLine/cac:InvoicePeriod/cbc:StartDate
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeSettlement/ram:SpecifiedTradeSettlementLineMonetarySummation/ram:BillingSpecifiedPeriod/ram:StartDateTime
```

## Create an XRechnung from your PDF

The converter reads the invoice and shows the fields it found before download, so you can check and correct the values. No PDF? Fill in the XRechnung directly in the form.

- [Convert invoice](/en/pdf-to-xrechnung)
- [Fill in XRechnung in the form](/en/create-xrechnung)

Download requires an account. Subscriptions from €10/month with annual billing (excl. taxes), or €5 per conversion (excl. taxes) without a subscription.

## Why the standard cares about this field

### Business Context
Used for services or subscriptions with specific billing periods.

### Legal Requirement
Optional according to EN 16931-1.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)