Box 2a shows the taxable amount, and Box 2b has two checkboxes: "Taxable amount not determined" and "Total distribution. " When the first box isn't checked, it means the issuer has determined exactly how much of your distribution is taxable, and that amount appears in Box 2a. Here's how to use your basis to calculate what you actually owe. Does this mean the entire $2320. 00 is definitely taxable? I'm pretty confused about what this means for my tax return. However - We see box 2b is checked, which contradicts 2a, by saying (TAXABLE AMOUNT NOT DETERMINED). Just wondering if this is. Direct rollovers between plans use G, and designated Roth account rollovers to Roth IRAs use H. Where Do You Report 1099‑R Amounts On Form 1040? You will report IRAs on lines 4a and 4b and pensions or annuities on. Forms 2, 3 and 4 are further broken down into Form 2a, 2b, 3a, 3b, 4a and 4b. Each Form relates to the internal separation of the busbars, functional units and terminals, each being defined as: Internal separation is achieved by the use of barriers or partitions (including metallic or. The table below lists the account types, the corresponding 1099-R box numbers, and the withholding references. Tax codes applicable to this table are listed in Applicable Tax Codes (page 3).