Can you ask for a raise after 3 or 6 months?

You can ask for a raise after three or six months if something concrete changed: you took on duties beyond your original role, delivered a clear result, or found out you were hired below the market range. Without one of those, it's usually better to gather evidence and ask at the first annual review.

Good reasons to ask early

You absorbed work from someone who left
You delivered a result with numbers your manager can verify
You learned the role pays below the market range in your area
You were told at hiring that pay would be reviewed after a period

Reasons to wait

Your only argument is time in the job
You don't have results yet that your manager would recognize
The company just announced a freeze or layoffs

How to ask early

"Since I joined, I've taken on [responsibility] and delivered [result]. I'd like to discuss whether my compensation can reflect that, or agree on what I'd need to show and a date to review it."

Asking for a review date is a reasonable outcome even when the answer today is no.

Questions

Can I ask for a raise after my probation period ends?

Passing probation confirms you're staying, not that your pay changes. It's a good moment to ask about the criteria and timing for a pay review.

Is 6 months too soon?

Not if your role changed or you're below market. Time alone is the weakest argument you can bring.