If a salesperson doubles his/her target, do you think it's fair for the company to decrease his/her commission percentage? Why?

I've never heard of a company decreasing commission just because they doubled their target. I am thinking this is a backwards company who has no idea how to motivate their employees and appreciate their efforts. 

Why so serious dear, it's normal where at some countries they still call employees (footman=اجير). We can expect even more like decreasing your salary at social security and more....

We can send a message here to all  senior HR managers: (Do not be deceived, bad company corrupts good morals.) 

                                                                                               Thank You.

No , if the company double the target must not just double the commission percentage it must also increase this percentage than the double and add more tools to achieve it . Otherwise the problem will be in the business plan .

Yes, indeed it is NONSENSE.

Targets are set upon several issues including personal capabilities. If this sales person is capable to sell more, he should have got higher target from the first place.

When setting targets, it is assumed that the sales person is capable to achieve something between90 -110%. Achieving less or more than that (very often) means, there is something wrong with target calculations.

It's a wrong/unethical approach that mounts to Business Unethics/Poor HR systems of the company.In such scenario concerned sales person should escalate the matter in writing within Company,escalation should happen in hierarchical manner such as from immediate boss till Head of the Dept..then to HR Dept and then to Head of the Company.In case of failure to get the dues cleared,the concerned sales person can approach to Labour Department of their jurisdiction,to get the justice/to get dues/compensation cleared

Sales incentive plans are announced with sales targets to be followed for the financial year. So the question of any revision does not arise unless justified which is mutually agreeable.

Company will increase the sales Target to maximize the goods sales out. 

No I don't think its fair as any sales person do hard work upon achieving sales target and by that wants to earn good incentive then why company always change its system.You are right it happens in most company when executive earn something more then company change incentive system, why. Now company is earning very high if any executive is earning something but that also company don't bear? company don't want to earn that executive or manager where as these companies wants to be listed in Forbes, but it is unjust and such companies don't grow much. Now my one of the colleague in this company earns6 lacs Rs then company says we cant pay this settle with him but top mngt. don't think how much bushiness he has given. Your question is very true in today's company atmosphere, everybody wants to be billionaire but don't want any one to be millionaire.

no, s/he should keep the commission due to earn it no wrong write  answer

in my personal view if somebody is achieving double of his target then the target distribution was not followed by proper planning and prior research. but i am dead against of decreasing the bonus or PLI. but a better approach should be considered before distributing the target next time

It is in the favor of company goodwill.Because if the salesperson double his target there is no decrease in his commission actually he is increase or boost up the sale volume of the company and company also increase the commission percentage of salesperson