Where did the Line 16a1 number come from in my Form 1116?

Form 1116 line16 Adjustments to line 15 (see instructions)

Instructions for form 1119

Line 16

You are required to increase or decrease the amount on line 15 by the following adjustments. The adjustments must be made in the order listed. If you have more than one adjustment, enter the net adjustment on line 16 and attach a detailed statement showing your computation. See Pub. 514 for more details on these adjustments.

The adjustments are as follows.

1. Adjustment for disallowed business loss under section 461(l).

• Increase the amount on line 15 by the amount of any business loss that is disallowed under section 461(l) to the extent it is attributable to the separate category of income of the applicable Form 1116. 
• For purposes of adjustments 2–6 described below, any reference to an amount on line 15 shall mean the amount on line 15 after taking into account this adjustment for disallowed business loss.

2. Allocation of foreign losses.

• If you have a loss on line 15 of one Form 1116 and you have income on line 15 of one or more other Forms 1116, you must reduce the foreign income by a pro rata share of the loss before you use any remaining loss to reduce U.S. source income.
• If the loss reduces foreign source income, you must create, or increase the balance in, a separate limitation loss account and you must recharacterize the income you receive in the loss category in later years. See 5. Recapture of separate limitation loss accounts , later. In situations where the loss to be allocated exceeds foreign income in other categories:
• The excess reduces U.S. source income (as modified under Capital losses next);
• You must create, or increase the balance in, an overall foreign loss account; and
• For later years, you must follow the rules described under 4. Recapture of prior year overall foreign loss accounts , later.

If the loss in one category reduces foreign source income in another category and that second category has a separate limitation loss account with respect to the first category, then the two offsetting separate limitation loss account balances are netted for purposes of determining the amount of income in either category that is subject to recharacterization under 5. Recapture of separate limitation loss accounts , later.