Tax Code Detection

What does this script do?

Automatically determines the correct tax code based on the document's fulltext content and tax/net amounts. Detects reverse charge scenarios, tax-free invoices, and calculates the tax rate to assign the appropriate code (e.g., S1 for 19%, S2 for 7%).

Trigger

AFTER_FORMATTING on document type INVOICE

Full Script

# Get document fulltext and amounts
content = get_document_content(document_data)
tax_amount = get_field_value(document_data, "tax_amount", "0")
net_amount = get_field_value(document_data, "net_amount", "0")

try:
    tax = float(tax_amount) if tax_amount else 0
    net = float(net_amount) if net_amount else 0
except ValueError:
    tax = 0
    net = 0

# Rule 1: Reverse charge detection via fulltext
if "REVERSE CHARGE" in content.upper() or "UMKEHR DER STEUERSCHULD" in content.upper():
    set_field_value(document_data, "tax_code", "RC")

# Rule 2: Zero tax = tax-free
elif tax == 0:
    set_field_value(document_data, "tax_code", "Z0")

# Rule 3: Calculate tax rate from amounts
elif net > 0:
    tax_rate = round((tax / net) * 100, 0)
    if tax_rate == 19:
        set_field_value(document_data, "tax_code", "S1")    # Standard rate
    elif tax_rate == 7:
        set_field_value(document_data, "tax_code", "S2")    # Reduced rate
    else:
        set_field_value(document_data, "tax_code", "S3")    # Other rate

Step-by-Step Explanation

1. Read fulltext with get_document_content() for keyword detection

2. Read tax and net amounts for tax rate calculation

3. Check for reverse charge keywords in the document text (German and English)

4. Check for zero tax — if tax amount is 0, assign tax-free code

5. Calculate tax rate from tax/net ratio and assign the matching code

Functions Used

• get_document_content() — Read OCR fulltext

• get_field_value() — Read field values

• set_field_value() — Set tax code