What is the CISG and does it apply to my international invoices?

The CISG governs international goods contracts between businesses in the 97 countries that have ratified it, including the US, EU members, China, Canada, and most major trading nations. When a US seller delivers goods to a buyer in another CISG country, the treaty's rules apply automatically to formation, performance, breach, and remedies — unless the contract explicitly states that it is excluded ('The parties exclude the application of the CISG').

Key CISG rules that differ from US UCC: acceptance of an offer can modify its terms without being a rejection (unlike the UCC's 'battle of the forms' rules); the buyer must give timely notice of defects or lose the right to claim breach; the seller's obligations are stricter in some circumstances. These differences matter when enforcing an unpaid international invoice.

The CISG does not apply to: service contracts, mixed goods-and-services contracts where the primary value is services, personal/household purchases, and certain industries (auction sales, financial instruments). If your international engagement is primarily services, the CISG likely does not apply.

For international invoices, the governing-law clause in your contract controls which country's substantive law applies (separate from CISG). If the contract is silent on governing law, international choice-of-law rules apply — which is why a US-law, US-venue clause in every international contract is strongly recommended.