For a full license holder in Texas who is over 21 years of age, the legal blood alcohol concentration (BAC) limit for driving is 0.08% . For commercial drivers holding a CDL, the legal alcohol limit for driving is only 0.04%, regardless of whether they are driving their commercial or personal vehicle. If caught with a BAC of 0.15% or above, the punishment category can be bumped up to a Class A misdemeanor. It is important to note that the legal limit of 0.08% does not mean that the BAC limit is 8% mathematically. Instead, it means 0.0008% . For drivers under 21 years of age, it is against the law to drive with any amount of alcohol in their blood.