It's tied, but indirectly. Completion of chores properly is obviously required for allowance to be received. But it was important to us to not give the impression that this was "pay for work done". Rather, the work has to get done, the payment is for doing it properly and without complaint (ie. to save my and my wife's sanity).

But the important bits are:

1. The job gets done always. There is not an option for the child to say "keep your $2, I'd rather watch TV today."

2. If the job isn't done right, the child has to re-do or otherwise complete the job.

3. Complaints about the job, or failure to do the job promptly (ie. nagging), lead to deductions in allowance, but #1 still applies.

4. The size of the allowance and the size/number of chores are not directly related.

We also give the kids the option to change chores (within reason) - because the allowance isn't tied to specific chores. As they get older, they get more responsibility (more and/or more complex chores) but also more allowance.

Like I said, it seems to work well for us. The chores range from feeding the cats to doing a load of washing to helping cook dinner. They quickly learn that complaining about chores is a no-win situation, and accept that it's simply a part of week to week life.