Short answer: It depends on your car. Honda calls for new brake fluid every 3 years. Toyota's 2025 Corolla Cross schedule only calls for checking it. Your owner's manual is the place to check.
We're not mechanics, so the facts below come straight from carmakers and the Federal Trade Commission. The sources are linked at the bottom.
What a brake fluid flush is
It's a service where a shop pushes new brake fluid through your brakes until the old fluid is out. Carmakers call it changing or replacing the brake fluid.
What carmakers say
Honda, in its owner's manual: change the brake fluid every 3 years.
Honda, in a 2019 position statement for its Acura cars: "Brake fluid changes should be recommended in accordance with the Acura owner's manual, and no more than once every three years."
Toyota, in its 2025 Corolla Cross maintenance guide: brake fluid gets checked every 5,000 miles but isn't on a replacement schedule. The guide adds that a dealer may recommend more service based on that check.
What the FTC says
The Federal Trade Commission tells drivers to "follow the manufacturer's maintenance schedule in your owner's manual for your type of driving." It also notes that some shops create their own maintenance schedules, "which call for more frequent servicing than the manufacturer's recommendations."
What to say at the counter
"Is new brake fluid due on my car's maintenance schedule? If not, why do you recommend it?"
The FTC suggests asking a shop to explain "why it recommends service beyond the recommended schedule."
For other cars
Check the maintenance schedule in your owner's manual. If new brake fluid isn't due yet, ask the question above.
Got an estimate with a brake fluid flush on it? Backseat Mechanic members text us a photo of it and find out what to fix today, what can wait, what to skip and whether the price is fair. See how it works
This is general information, not a diagnosis of your car. If your brake pedal feels soft or a brake warning light comes on, get your brakes checked right away. Your owner's manual is the final word.
Sources