This app was mentioned in 2 comments, with an average of 1.00 upvote
SSI recipients can earn up to $2,000 a month without effecting their insurance. You will need to report the monthly income from Perk to the Social Security Administration. This can be done online, through their app, or you can call an report the income through their automated telephone service. However, they will deduct money from your benefits based on the previous months earnings (I want to say $1 per $2 made after a certain threshold.) Needless to say, you will make more money per month if you earn additional income aside from SSI benefits.
If you do not foresee exceeding past $500 total from Perk, then I, personally, would not bother with reporting it to the SSA or filing. If you do plan on and foresee on passing said threshold, I encourage you to report the wages to the SSA monthly- your reports to the IRS at the end of the year will need to be close to the wage reports you send to the SSA or you may have to pay some money back.