General Deduction Rules: Old Sections 80A, 80AB, 80AC And 80B Are Now Section 122

Before you ever get to a specific deduction, an 80C investment, an 80D health premium, an 80G donation, there is a layer of ground rules that governs how any deduction under Chapter VI-A can be claimed at all. Under the old Act, that layer was spread across four separate sections. Under the new Act, all four are consolidated into a single section that opens the entire deduction chapter.

Old law: Sections 80A, 80AB, 80AC, and 80B, Income Tax Act, 1961

New law: Section 122, Income Tax Act, 2025, effective 1 April 2026, applicable from AY 2026-27

What the Old Sections Said

Each of the four old sections did a distinct job:

• Section 80A: the aggregate of all deductions claimed under Chapter VI-A cannot exceed the assessee's gross total income. You cannot use deductions to push your income below zero or generate a loss
• Section 80AB: where a deduction is computed with reference to income of a particular nature that is included in gross total income, the deduction has to be calculated on the net income of that nature actually included, not the gross figure before any adjustments
• Section 80AC: certain deductions are not allowed at all unless the return of income is furnished on or before the due date specified for filing. Miss the due date, and specific deductions, including several profit-linked ones, are simply denied
• Section 80B: the definitions section, most importantly defining gross total income itself as total income computed before making any deduction under this Chapter

Individually, these four sections rarely got quoted by name in client conversations, but together they formed the guardrails that every single deduction claim under 80C to 80U had to operate within.

What Actually Changed

The new Act folds all four provisions into Section 122, positioned as Part A, the general provisions, at the very start of the new Chapter VIII deduction framework. The chapter itself is now organized more systematically than the old Chapter VI-A:

• Part A, Section 122: general provisions governing all deductions in the chapter, consolidating old Sections 80A, 80AB, 80AC, and 80B
• Part B, Sections 123 to 137: deductions linked to specified payments, such as life insurance, provident fund, health insurance, and donations
• Part C, Sections 138 to 152: deductions tied to specified incomes, largely the profit-linked deductions for particular business categories
• Part D, Section 153: deductions for other incomes
• Part E, Section 154: deductions for other qualifying payments or persons

The substance carried over from the four old sections remains intact within Section 122: deductions still cannot exceed gross total income, deductions still have to be computed on net income of the relevant nature, return filing by the due date is still a precondition for specific deductions, and gross total income is still defined the same way. What changed is that a practitioner now reads one section to understand all four ground rules, instead of cross-referencing four scattered provisions.

Worked Example

Old position, Sections 80A, 80AB, 80AC, 80B, applicable up to AY 2025-26:

Mr. Thakur runs a small manufacturing unit and has gross total income of Rs. 6,00,000 for FY 2025-26. He claims Rs. 1,50,000 under Section 80C, Rs. 25,000 under Section 80D, and is also eligible for a profit-linked deduction of Rs. 5,00,000 under a specified business incentive provision. However, he files his return three months after the due date. Under Section 80AC, the profit-linked deduction is denied entirely because of the late filing, even though he would otherwise have qualified. His 80C and 80D deductions, not covered by the 80AC restriction, remain allowed. Applying Section 80A, his total allowed deductions of Rs. 1,75,000 do not exceed his gross total income of Rs. 6,00,000, so the full amount is allowed, bringing his total income down to Rs. 4,25,000.

New position, Section 122, applicable from AY 2026-27:

Same facts, same business, repeated in FY 2026-27, with the return again filed three months late. Section 122 now governs all of this in one place. The profit-linked deduction is denied due to late filing, exactly as Section 80AC required before. The 80C and 80D-equivalent deductions remain allowed, and the aggregate deduction of Rs. 1,75,000 is checked against gross total income under the same cap principle. The outcome is identical, total income of Rs. 4,25,000. Only the section citation changes, from four separate old sections to Section 122 alone.

Why This Matters for Filing

• The due-date-linked denial, formerly under Section 80AC, remains one of the most commonly missed compliance points. Any client claiming profit-linked or specified business deductions needs to file on or before the due date without exception, since this restriction has not softened under Section 122.
• When computing deductions tied to a particular type of income, always use the net figure actually included in gross total income, not the gross figure before adjustments, consistent with what old Section 80AB required and what Section 122 continues to require.
• Always run the aggregate deduction check before finalizing a computation. No combination of Chapter VIII deductions can push total income below zero or create a loss purely from deductions, a rule now sitting in Section 122 rather than the old Section 80A.
• Since Section 122 sits as Part A ahead of every specific deduction section from 123 onwards, treat it as the first section to review whenever a new deduction claim is being evaluated, not an afterthought once the specific deduction section has already been checked.

Bottom Line

Old Sections 80A, 80AB, 80AC, and 80B have been consolidated into a single Section 122, forming Part A of the new Chapter VIII deduction framework. Every rule that mattered before, the gross total income cap, net income computation, due-date-linked denial, and the definition of gross total income itself, carries forward unchanged. What is different is that practitioners now have one section to check instead of four scattered ones, positioned deliberately at the start of the chapter so it governs everything that follows.