"Homer Simpson" wrote
A "high estimate" of your income is whatever you put into the bank + for any claimed cash expenditures. Said cash expenses not being allowed due to your inability to keep records (ie: unable to prove).
In an audit they'll not add up your records for you. They'll verify that the amount you reported for a claimed expense has support. No support? Then you get $0 deduction. After about three or four of those, they zero all claimed expenses and close the audit. Additional taxes, penalties and interest.