the taxman uses Form 26AS as his ready-reckoner to pick up details related to your incomes, investments, big-ticket purchases spends and tax liability for the year. To calculate how much you owe, the tax officer matches the details in your Form 26AS with what you have declared in the tax return.It is your annual tax statement issued by the income tax department. It contains details of your tax deducted at source (TDS), taxes you paid, refunds received, and other tax-related information. The form also acts as a consolidated record of your tax deductors and collectors.