CII-DT-068: Write the invoicing period start as a plain date

What it means

The invoicing period (BG-14), or the period on a line (BG-26), sits in BillingSpecifiedPeriod. Its start date (BT-73, or BT-134 on a line) goes in StartDateTime. This rule checks that StartDateTime does not hold a DateTime element, which is a full date and time value. EN 16931 uses the plain date form, DateTimeString.

Why it matters

The standard fixes the form in which this date is written so that every receiving system reads it the same way. A start date written another way does not meet it, so the file fails and is rejected.

How to fix it

Look in the e-invoice or XML export settings of your invoicing software and choose the standard EN 16931 output. If you build the XML yourself, replace the DateTime element inside StartDateTime with DateTimeString, set its format attribute to 102 and write the date as YYYYMMDD. Check the end date in the same way, as it has its own rule.

The rule as published

DateTime shall not be used.

Where this rule applies