The "going rate" is a dollar a year. Out of that cash, your child should be expected to manage it one of several ways:
1. Save and spend
2. Save, spend and donate
3. Save, spend, donate, invest
4. Whatever you negotiate!
Make a written agreement. Their memories are short, especially when they feel that they absolutely, positively gotta have it...whatever "it" is! And, let's face it, we're the parents, we've got a lot swirling around in our brains.
The next big question is: "What do they have to do to earn it?" The answer is: "Whatever I ask you to do" as long as it's reasonable considering their age and skill set (well, of course!) and that the task or activity must be executed with genuine effort (not a half-baked effort) and a positive attitude (no mumbling under their breath or slamming "things" around!). You might want to focus on "family behavior" instead of specific chores.
Family behavior is whatever conduct you choose such as respect, consideration, cooperation, no "sassing" or back talk or starting fights with your brother!! A couple of hints here:
1. Focus on the two or three behaviors that cause disruption, drive you crazy, whatever and SPELL out "what" the behavior "looks like" ("You walk by your brother and stick out your tongue").
2. Respect means speaking kindly (voice, sarcasm, inflammatory language such as ......)
3. Cooperation means that you say "Sure, Mom!" when I ask you to take out the trash for the second time that day.
4. Respond to me promptly. Don't make me ask you a second time. This means, Mom and Dad, that when you give you child a "task", you use "effective" communication skills. Have their attention, speak directly to them, DON'T OVERTALK, and clarify that they understand by asking, "Now, tell me what you are to do". Don't ask them to repeat...if they tell you WHAT they are going to do, it means they've processed the request and are thinking about a plan.
At the end of the week, ask them what portion of their allowance they think they've earned. Don't just hand it to them and go on your merry way! You tell them what you think they've earned and find the middle ground. If you have evidence of a disappointment (loss of cash) or a spectacular "win", tell them BRIEFLY and move on. Give them a hint or two about how they can improve their performance.
Young children or children with impulsivity or other behaviors that "get in the way" may need the "reward" or "review" at the end of each day in order to get a better sense of how to improve their performance the next day AND to keep them motivated to work with you to help the family.
AVOID overtalking this or they'll emotionally "drop out" and it won't be meaningful.