CII-SR-454: Use exactly one VAT entry per line settlement

What it means

For each SpecifiedLineTradeSettlement on a CII invoice line, the test requires exactly one direct ApplicableTradeTax child. It counts entries; it does not check that the settlement section exists or that the category and rate values are correct.

Why it matters

A single VAT entry gives the line one VAT treatment for the VAT breakdown. Whether a VAT rate is required depends on the category, not on this entry-count check.

How to fix it

In the affected SpecifiedLineTradeSettlement, add the missing ApplicableTradeTax or remove duplicate entries after checking the correct VAT treatment. Set the VAT category (BT-151) and supply the VAT rate (BT-152) where applicable. If a line combines supplies with different VAT treatments, split them into separate lines and review their amounts. Recheck your file.

The rule as published

Only one ApplicableTradeTax should be present

Where this rule applies