Last year was my first year doing mystery shopping. When/how do we get a 1099 form for filing 2019 taxes? Thank you.

You should get a 1099 in either U.S. mail or email (for online access) for every MSC from which you have earned $600 or more. However, some MSC's, especially some of the smaller ones, sometimes struggle with this. I have received most of mine already. Note that iSS (i Secret Shop) is NOT such an MSC - it is a platform that allows MSC's and shoppers to hook up. If you do not receive all your 1099's, you'll still be fine to do your taxes without them - so long as you have good enough records that you report at least as much income as was reported by MSC's to the IRS.

Great, thank you so much for the great answer! Helps a lot.