Apologies, I'm new at SE taxes and business taxes. I have a few questions if anyone would be willing to share their experiences.

Is there a benefit or reason to choose cash vs. accrual for accounting? I track my jobs but also track when I get paid so I could likely do either.

Is it better to list the total amount paid and then list deductible expenses or is it better just to list the profit? I brought in low five figures last year with about 65% of my money coming in going towards reimbursements. I think I read something about having a fuller schedule C if you ever needed it for credit cards or loans, etc. but I don't recall the details.

What level of detail is needed for the taxes? Can you put $xx,xxxx for mystery shopping income and $x,xxxx for mystery shopping reimbursements? Would reimbursable expenses fall under "other expenses?" Or, does it need to be much more detailed like $x from ipsos and $y from marketforce? Do I need to break out reimbursements per company or per location shopped (e.g. $x at kroger)? Surprisingly I did not receive a 1099 from any of the companies I worked for but I don't think I cleared $600 in pay with any one company. This makes me think again about cash vs. accrual - in the future, depending on which I choose, would it matter if/when I receive 1099s in the future?

Thanks to anyone who can lend some support and suggestions. I appreciate it SO much!

I can't really say if one is better than the other, but I do cash for simplicity, I list it all as one lump sum (as opposed to per company). I do not list reimbursed expenses. I deduct some expenses like mileage, a portion of my cell phone bill, but I don't go overboard. I also lump together the mileage as one number. I haven't done my taxes yet this year so its not all fresh in my head but I figure if I get audited, I have the detailed information in my spreadsheet and pics/records of receipts to back up my numbers.

I use accrual and also have not yet done my taxes. The schedule C gives you places to add these items. It really does not matter whether you get a 1099 or not as the tax basis is the same either way. In my case all my records are kept by the year I actually do the shop. It just seems neat to my brain to do it that way. I close the year on Deb 31st.
Since you have already done all your calculations and know the figures for reimbursements , write offs and expenses out of flat fee amts it is easy for you to put them down (in one number for each category) on the tax form. I make a lot of decisions based on my interpretation and the gut feeling after thorough research and in this case it feels like it might look a bit shady to me not to list your reimbursements amount. I have it all and do not plan to cheat so I just lay it all out. I am ready with my numbers and do not have to scramble should the IRS want to know more.

I use accrual because my first year shopping it was beneficial for me tax-wise to report a higher income that year. I still prefer it because I don't have to track payment dates. Either way is fine.

I don't break down my income by MSC, so I would not break down reimbursements either.

I use the cash method and have for decades (various businesses going back to 1980 or so). That way I claim expenses in the year that I actually spend the money. When the reimbursement arrives, it is revenue at that point. For me, a key point is the fee. Suppose you do a shop on December 15, 2022. Using accrual, you have to book the revenue for TY 2022. On January 15, 2023, the MSC tells you that the client has rejected your shop and you won't be reimbursed and you won't be paid. Since you used accrual, you have to report the revenue for TY 2022. Someone may argue that if you haven't filed your taxes yet, you can just fix your records. So, let's move the notification date to February 2023 which is not unrealistic for some MSCs. You filed your taxes on February 10th. You won't be able to claim the loss (it is now a loss because you reported accrual income that did not arrive) until you file for TY 2023 in February 2024.

I find it much easier to use the cash method. Cash goes out in 2022, it goes in the TY 2022 return. Cash comes in during 2023, it goes on the TY 2023 return.

Be aware, that once you make an election either way, you have to continue to use that method unless you ask the IRS for permission to change.