The most common reason for tail pushing is speed control. As JASP has noted there are many possible reasons why your brain is deciding you need to throw on the brakes. As such, there are lots of drills that can help fix tail pushing. Which one will work the best for you is best decided by a trained eye on site, but if you're the type that does not mind throwing stuff at the wall to see what sticks here are some ideas.
Garlands with progressively deeper dips down the hill until you are doing one large turn to a stop using the whole trail width.
Railroad tracks on cat tracks, green trails and blue trails. Turns can only be made by tipping the skis. Tracks must be pencil thin (on firm snow, no more than 2" wide in soft snow) throughout the whole turn. Perfect the technique on flat runs and move to steeper runs. Speed on the blue trails should ramp up to really scary. Corduroy snow is best.
Skate turns. Start with medium size garlands, but skate step 2 steps up the hill during the uphill part of the garland. Then do one garland with the skate steps, but skate step 2 steps down hill into a new turn (use small smooth steps). After the steps, turn uphill to a smooth stop. Change to one step. Then link turns. Then only step down into the new turn. Then do the same movements without stepping.
Thousand steps/shuffles. Make lots of tiny steps or shuffles of the feet constantly throughout your turns.
Cowboy turns. Stand with your feet wider than shoulder width apart. Make turns by extending your mass to the inside of the downhill ski instead of leaning into the new turn.
Inside hip forward. Try to make turns by thrusting your new inside hip forward as your first move. This is counter intuitive and not a move that we want to incorporate into our skiing, but it will mess with your head.
For the purpose of making up something to say, there are two basic approaches to solving tail pushing problems:
-introducing new movements to replace tail pushing
-changing the mental attitude towards speed control
Sometimes merely focusing on the concept of rounding out the upper and lower parts of the turn can cause the brain to let speed control happen in other parts of the turn (via new movements) besides just after entry into the fall line. Other times a direct focus on ankle/knee/hip/etc movements is required before the need to tail push is eliminated. Sometimes the slope must be flattened before anything else can be done. Your vertical may vary.