I have a 6 year old daughter that constantly takes stuff. She does not acknowledge taking it or saying that she did it. The recent case was when our 10 year old son missed his money out of his safe. Our 6 year old daughter had obtained some money from somewhere in her room (she says). She knew where his billfold was and where she had counted his money. She said she found the money in her drawer in her billfold. She is very angry because we made her give Her money back to him . Help. Has anyone experienced this?

My kids tried pulling this a lot. I have also seen other kids do this. Even adults.
They are often so in denial that they really believe their own stories.
You may have to get a hidden camera and show her physically doing things she denies.
I have noticed, with adults anyway, it is like they are in a brain fog and don't realize their own actions.

It's not kleptomania. Kleptomania is truly not being aware of taking something not your own. It sounds like your daughter is very aware of what she is doing.

I suggest you make an appointment for a few sessions with a child management specialist who will talk with you as parent(s) and also bring your daughter into sessions. Along the way, you should be able to find out why she is acting this way and various things you can do to reframe her way of thinking (plus maybe give you some parenting tips).

I think kids sometimes act like this for some sense of security they feel they are lacking.
It is their way of acting out if they feel they aren't getting the attention they want or something.
First she needs to face the fact she is doing this and how disruptive it is.
Counseling may be the only way she can get help since she is in denial and probably has no idea what makes her do it anyway.

probably has no idea what makes her do it anyway.

Or maybe her brother just gets better stuff! (she thinks)

Often "stuff" is tied to love. Maybe she's unconsciously wanting more love.

What punishment did she receive for doing this ?

Or maybe her brother just gets better stuff! (she thinks)

Often "stuff" is tied to love. Maybe she's unconsciously wanting more love.

Exactly what I meant :D