If a distribution was done from your IRA or other retirement account during last year, the payer should have sent you a Form 1099-R. Your Form 1099-R should have been mailed/shipped by January 31 of this year, unless the payer filed for an extension.
Form 1099-R is your distribution statement, and includes information such as how much of the amount distributed is taxable, and whether or not the distribution is subject to a 10% early distribution penalty.
While payers often do their best to ensure that the information reported on Forms 1099-R is correct, mistakes can be made.
Also, even if their reporting is correct- as determined by the IRS’s instructions- your tax preparer might need to make modifications on your tax return.
For example, if your custodian reports your distribution from your traditional IRA as fully taxable, but only a portion of the amount is taxable because you had after-tax amounts in your traditional IRA, your tax preparer will need to file IRS Form 8606 to let the IRS know how much of the distribution is taxable income which is nontaxable.
 Your payer is your IRA custodian/trustee or trustee of your 401(k) or other employer-sponsored retirement plan.