It depends. If you happen to have soy milk that has passed its date, it is advisable to discard it. But, it is not impossible that soy milk may still be good surpassing its expiry date. If you’re trying to reduce food waste and hesitate to throw it right away, try to check signs of spoilage. If spoilage signs are not found and the quality is acceptable, feel free to drink. But, try not to keep soy milk too long after its expiration date for safety reasons.