Consider going with it!
In some dances, like argentine tango and west coast swing, a follower can make ‘suggestions’ or even outright ‘hijack’ the movement. This is fine, as long as they don’t lead the majority of steps, and you can actually make the dance more fun by going along with it.
Avoid the step.
Your partner may be trying to steer you away from moves they don’t know, or might aggravate a past injury. If they seem to back-lead more on certain types of moves – dips for example, or multi-spins, you might want to just avoid those steps entirely.
Make sure you’ve balanced your partner properly.
Your partner might be back-leading – or they might be trying to keep their balance. When you dance, shift your weight 100% from one foot to another on every step, and make sure your partner is doing the same.
Increase the assertiveness of your lead.
Many followers fall into back-leading if they aren’t feeling enough lead themselves. So tighten up that frame, increase the pressure slightly, and make sure you never ‘leave your arms behind’ on any movement. They should move with your body, as one unit.
Gently let your partner know.
If your partner is still not getting the message, you might need to tell them, delicately, that they need to wait for you. This can range from a simple ‘would you mind waiting a bit longer for my lead?’ to the more risky but humorous ‘tell you what, you can lead the next one, what do you say?’
(Practice) Have them close their eyes.
If your partner is someone you practice with regularly, and the floor is not crowded, suggest they close their eyes while you dance. This forces them to rely completely on the pressure through your frame, instead of guessing the movement from what they see. Stick with the patterns you know best while trying this – no dips!
(Advanced dancers only!) Be creative!
This doesn’t work for everybody, but in my lessons, I’ve found it to be a good way to teach your partner not to anticipate if all else fails. Look for places where they tend to back-lead, like a spot turn. Then throw in a variation the next time you try it! Make sure it still meshes with the movement, and don’t sacrifice your technique. Will she be surprised? Very likely. Will she be more patient next time in case you try it again? Definitely!