Depends what your position of negotiation is. If you have a job currently and you don't necessarily NEED this job, you have a little more leverage. If you are unemployed and need a job, you may not want to rock the boat.

 

Another factor to take into play is growth potential at the new company. Are merit increases small? Is it easy to move up? Will you be stuck around your starting salary for a long time? Is this job a springboard to another job? 

 

Lots of factors to take into play IMO. In hindsight, I would have left that number blank when filling out the application. TJBender is right, now you come out looking bad if you try to change it. If you don't currently NEED the job, you could always bring up that after further research you realized the offer is a bit low, but that could also backfire and look like you weren't prepared in the first place.

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