The actress' case was under review by the L.A. District Attorney's Office and they've decided to charge her with driving under the influence of alcohol and driving with a .08% BAC.

TMZ broke the story ... the actress was found slumped at the wheel in Beverly Hills -- blocking the road with her car.

She was booked for DUI and improper stopping on a roadway -- but less than 24 hours later, was back onstage performing down in Long Beach -- not resisting a quick quip about her arrest.

However, Tiffany quickly changed her tune ... getting serious about the arrest -- especially as she already has a DUI case in Georgia stemming from Jan 2022.

In fact, in light of her Cali arrest, Georgia prosecutors are pushing for stricter restrictions on her -- wanting to modify the bond conditions from her open DUI case there to restrict her from using booze and drugs completely.

BTW ... if Tiffany is convicted of both offenses, both California and Georgia have laws that require jail time for a second offense -- in CA, the minimum is 4 days, in GA it's 3 days.

Tiffany's since told ET she needs to "get help" to "learn balance and boundaries" -- adding, "this will never happen again."