Mandatory Fields: GST invoices must include GSTIN, HSN/SAC codes, CGST, SGST, or IGST breakdown, and place of supply. Businesses with turnover above ₹5 crores must generate e-invoices.

Legal Requirement: Under the GST Act, 2017, registered businesses must issue tax invoices for all taxable supplies. Non-compliance can result in penalties up to ₹25,000.

E-Way Bill: For goods worth over ₹50,000, e-way bills are mandatory, requiring accurate invoice details for generation.

Time Limit: Invoices must be issued within 30 days of supply (45 days for services).

Sales Tax: 45 states and DC impose sales tax. Businesses must collect tax based on nexus rules. Professional invoices help track taxable vs. non-taxable sales.

IRS Requirements: While not federally mandated, invoices are crucial for tax deductions, business expense claims, and IRS audits. Proper documentation can save thousands in deductions.

State Variations: Some states like California require detailed invoices for certain transactions. Professional invoices reduce audit risk.

Business Credit: Well-documented invoices improve your business credit profile and help secure financing.

VAT Invoices Required: B2B transactions in the EU require VAT invoices with mandatory fields including VAT numbers, rates, and net/tax/gross amounts.

Country-Specific Rules: Each EU country has specific invoice requirements. For example, France requires invoices for transactions over €150, while Germany requires them for all B2B sales.

Digital Invoicing: Countries like Italy, Spain, and Poland mandate e-invoicing for B2B transactions. Proper formatting is essential.

Penalties: Non-compliant invoices can result in VAT disallowance and penalties up to €25,000 in some countries.