To help clarify this the surveys are provided by a third party and if you visit the Main Survey page you will see a list of surveys with the amounts listed. Some surveys if you are not qualified will route you to another survey if you do not meet the qualifications for the first.
InboxDollars only gets paid when a member gets credited for a successful completion.
If a member does not get a credit then InboxDollars does not receive credit.
Surveys will usually credit within 15 min, 30 min, 1-2 days and up to 3 weeks depending on the survey however you will get a "congratulations - your credit will be applied in X" telling you when you will receive a credit.
We have information on this in our Support Center: http://support.inboxdollars.com/hc/en-us/articles/201391009-How-long-does-it-take-to-be-credited-for-a-survey-

Recently I was not getting credited for surveys, which is why I chose to do paid/trial offers. But, when surveys did get accpeted & paid, it usually took about an hour & showed up on your balance. Recently, more & more people have complained about completing surveys & being rejected or stalled on the last page... so inboxdollars gets paid by the companies but we do not!