Forecast tax Your forecast tax estimate provides a projected calculation of the taxes payable for a specific financial period. It's determined by taking the difference between income and business expenses to find your business's profit. This profit is then multiplied by the applicable tax rate. Your individual tax rate may vary based on factors like your residential status, company structure, and taxable income. Estimated tax Estimated tax is a method used to pay tax on income that is not subject to withholding. This will typically include earnings from self-employment, interest, dividends and rent.