1099 vs W-2 for Traveling Trades Workers: What Actually Changes on the Road

1099 vs W-2 changes who pays the payroll tax, whether per diem can be tax-free, and who keeps the records. Here is what each one means for a traveling tradesperson, with the IRS sources linked.
Is Per Diem Taxable? Tax Home Rules for the Traveling Trades

Is per diem taxable? Usually not — while the work is away from your tax home, temporary, and paid within federal rates. Here are the three rules that decide it, with the IRS sources linked.