When you call the IRS, they will ask you to verify your identity. IRS phone assistors take great care to only discuss personal information with you or someone you authorize to speak on your behalf. To make sure that you do not have to call back, have the following information ready: Social Security numbers and birth dates for those who were named on the tax return An Individual Taxpayer Identification Number letter if the you have one Your filing status The prior-year tax return A copy of the tax return in question Any IRS letters or notices you received