Book to tax differences are items of income or expense that GAAP records in one amount or period and the tax code reports in another. Permanent differences like entertainment move your effective tax rate for good, while temporary ones like depreciation only move the year the tax gets paid. Form 1120 Schedule M-1 walks book income to taxable income, and indinero’s CPA-led close captures that detail in your QuickBooks Online or Xero all year.