The words extension as per GAFTA sound like a universal safety net. In practice, different forms give different rights, to different parties, for different periods and at different prices.
If the parties do not want any extension right, the contract should say so clearly: No extension allowed.
Under GAFTA 48 and GAFTA 100, extension may give the seller up to eight additional shipment days. The price allowance is predetermined: 0.5% for 1-4 days, 1% for 5-6 days and 1.5% for 7-8 days.
The mechanism applies only where the original shipment period is 31 days or less. A few extra days in the original period may remove the extension right entirely.
Under the latest versions of GAFTA 49 and GAFTA 64, extension gives the buyer up to 10 consecutive days to present the vessel. The buyer bears storage, interest, duty differences and other relevant carrying expenses.
GAFTA updates its standard forms. A reference to extension as per GAFTA without identifying the form and version may therefore produce an expensive mistake.
Extension does not operate automatically. Notice must be served by the deadline specified in the applicable form. Missing it may remove the entire extension mechanism.
Extension as per GAFTA sounds like insurance. But the emergency exit may belong to the other party, work differently from what you expected, or simply be painted on the wall.