How Income Tax Computation Works for Companies: Why You Can't Just Tax the P&L Profit, and What DTA/DTL Actually Mean

Ask most business owners how much tax their company owes, and the instinctive answer is: take the profit shown in the P&L, multiply by 25% or 30%, done. It's almost never that simple, and the gap between that back-of-envelope number and the actual tax liability is exactly where a proper income tax computation — and the Deferred Tax Asset / Deferred Tax Liability (DTA/DTL) entries sitting in every company's balance sheet — come from. This article walks through why the P&L profit is never the taxable number, how the computation is actually built line by line, and what DTA/DTL mean in plain terms, with a full worked example.

Why can't you just apply the tax rate to the P&L profit?

Because book profit and taxable profit are answers to two different questions, governed by two different sets of rules:

• Book profit (the profit in the Statement of Profit and Loss) is computed under the Companies Act, 2013 and Accounting Standards / Ind AS. Its job is to show a true and fair view of financial performance to shareholders, lenders and other stakeholders — so it recognises expenses like provisions, estimated liabilities and fair-value losses even before cash changes hands, and depreciates assets over their useful life on a rational, consistent basis.
• Taxable profit is computed under the Income-tax Act, 1961. Its job is to determine how much tax the government can fairly collect — so it often refuses a deduction until an expense is actually paid, disallows expenses that have nothing to do with earning income (like a penalty or CSR spend), allows depreciation at rates and methods prescribed under the Act rather than the Companies Act, and taxes some receipts the moment they're received even if accounting rules would spread them over future years.

Neither number is "wrong" — they're simply built for different purposes. The Income-tax Act doesn't ask a company to redo its books; instead, it starts from the net profit as per the Profit and Loss Account and works through a set of statutory additions and deductions to arrive at taxable income. That reconciliation is literally what the tax computation is.

The building blocks: from book profit to tax payable

Every company tax computation, however complex, follows the same skeleton:

1. Start with Net Profit as per the Statement of Profit and Loss (before tax).
2. Add back inadmissible/disallowed expenses that were deducted in the books but are not allowed under the Income-tax Act — e.g. depreciation as per books, provisions not yet paid, penalties, income tax itself, expenses hit by Section 40(a)(ia) for TDS default, or Section 43B items unpaid before year-end.
3. Add income taxable under the Act but not credited to the P&L, or credited at a different value — rare, but can arise from specific deeming provisions.
4. Less: Depreciation as per the Income-tax Act, computed separately under Section 32 (WDV method, block-of-assets concept) — completely independent of the depreciation charged in the books.
5. Less: Expenses allowable under the Act but not fully claimed in the books, and amounts now actually paid that were disallowed under Section 43B in an earlier year (e.g. last year's unpaid bonus, paid this year).
6. Less: Income exempt or not chargeable under the Act that was credited to the P&L — e.g. specific exempt income under Chapter III, where applicable.
7. Arrive at Gross Total Income, then apply any eligible deductions under Chapter VI-A (mostly unavailable under the concessional regimes) to reach Total Taxable Income.
8. Apply the applicable tax rate — normal rates, or the concessional rate under Section 115BAA/115BAB if opted — to get the tax payable under normal provisions.
9. Check Minimum Alternate Tax (MAT) under Section 115JB — companies on the normal/old regime must separately compute 15% of "book profit" (a differently-adjusted figure, not the same as taxable income) and pay whichever of the two — normal tax or MAT — is higher. Companies that have opted for Section 115BAA or 115BAB are outside MAT altogether.

Building this reconciliation correctly, client after client, means tracking every disallowed provision, every Section 43B item, every difference between book and tax depreciation on every asset block — the exact kind of structured, rule-based work that's error-prone in a spreadsheet. assureOffice's Financial Builder generates the P&L and Balance Sheet from Tally and carries the figures straight into a tax computation module, so the reconciliation doesn't have to be rebuilt by hand every year. See how assureOffice handles it →

The current corporate tax rates (AY 2026-27 / FY 2025-26)

Regime	Base rate	Surcharge	Cess	Approx. effective rate
Normal provisions — turnover up to ₹400 crore (in FY 2023-24)	25%	7% / 12% (income slab-based)	4%	~26.0% to ~29.1%
Normal provisions — turnover above ₹400 crore	30%	7% / 12%	4%	~31.2% to ~34.9%
Section 115BAA (any domestic company, concessional)	22%	flat 10%	4%	25.17%
Section 115BAB (new manufacturing companies)	15%	flat 10%	4%	17.16%
Foreign companies	35%	2% / 5%	4%	varies

A company opting for Section 115BAA or 115BAB gives up most deductions and incentives (additional depreciation, SEZ deduction, investment-linked deductions, and so on) in exchange for the lower rate, and the option, once exercised, is not reversible. This is exactly why two companies with identical book profit can end up with materially different tax liabilities depending on which regime they've chosen.

A full worked example

Assume a domestic manufacturing company (not opting for 115BAA/BAB, turnover under ₹400 crore) reports the following for FY 2025-26:

Particulars	Amount (₹)
Net Profit as per Statement of Profit and Loss	1,00,00,000
Add: Inadmissible items debited to P&L
Depreciation as per books	18,00,000
Provision for gratuity (unpaid, not to an approved fund)	4,00,000
GST payable, unpaid before the due date of filing return (Sec 43B)	2,50,000
Penalty paid for a statutory violation	1,00,000
Corporate Social Responsibility (CSR) expenditure	3,00,000
Income-tax provision for the year	10,00,000
Total additions	38,50,000
Less: Allowable items not in the books / deductions
Depreciation as per Income-tax Act, Section 32	22,00,000
Last year's GST disallowed under 43B, actually paid this year	1,80,000
Total deductions	23,80,000
Taxable Income	1,14,70,000
Tax @ 25% (turnover ₹400 crore or less)	28,67,500
Add: Surcharge @ 7% (income between ₹1 crore and ₹10 crore)	2,00,725
Add: Health & Education Cess @ 4%	1,22,769
Total Tax Payable	31,90,994 (approx.)

Notice that on a book profit of ₹1 crore, the actual taxable income comes to ₹1.147 crore — meaningfully higher, driven mainly by the provision for gratuity, the unpaid GST liability, CSR spend and the tax provision itself, only partly offset by higher tax depreciation. A flat 25% on the ₹1 crore book profit would have understated the liability by roughly ₹3.7 lakh before surcharge and cess. This is precisely why the reconciliation step can never be skipped.

The items that most commonly cause book profit and taxable income to diverge

• Depreciation — books follow the Companies Act (Schedule II, useful-life based, usually SLM or WDV per asset); tax follows Section 32 (block-of-assets WDV, prescribed rates). The two almost never match in any given year.
• Section 43B items — statutory dues (GST, PF/ESI employer contribution, bonus, leave encashment, interest on loans from specified financial institutions) and now, dues to Micro/Small MSME suppliers under Section 43B(h) — allowed only in the year actually paid, regardless of when the liability was booked.
• Provisions and estimated liabilities — provision for doubtful debts, provision for warranty, provision for gratuity not funded through an approved gratuity fund — booked as an expense under accounting standards the moment they're probable and estimable, but disallowed for tax until the underlying event (write-off, actual payment, approved-fund contribution) occurs.
• Disallowed expenses on principle — income tax itself, penalties and fines for infringement of law, CSR expenditure under Section 135 of the Companies Act (specifically disallowed under Section 37(1)), and expenses on which TDS was deductible but not deducted/deposited (Section 40(a)(ia), typically 30% disallowed).
• Capital items routed through the P&L — under Ind AS, certain fair-value gains/losses on investments or biological assets flow through profit or loss even though they're unrealised; tax law generally taxes such gains only on actual transfer/realisation.

So where do DTA and DTL come from?

Here's the accounting problem this creates: if the P&L shows a profit of ₹1 crore, but the company actually has to pay tax on ₹1.147 crore of income, then the tax expense shown in the P&L cannot simply be the cash tax paid — because some of that extra tax relates to items that will reverse in future years (like the GST paid late this year, or the gratuity provision that will become deductible once it's actually paid out). Accounting standards (AS 22 / Ind AS 12) require that the tax expense recognised in the P&L reflect the tax consequence of all transactions recognised in that period's books — not just the cash payable this year. The mechanism that bridges this gap is deferred tax.

The key distinction that decides whether a book-tax difference creates deferred tax:

• Timing (temporary) differences — the item will eventually be recognised for tax purposes too, just in a different year. Depreciation, Section 43B provisions, and unpaid statutory dues are classic examples: the expense is booked now but allowed for tax later (or vice versa). These create DTA or DTL.
• Permanent differences — the item will never be recognised for tax purposes, in any year. CSR expenditure and penalties are permanent differences — they're added back this year and will never be deductible in any future year either. These do not create any DTA/DTL — they simply increase tax payable, full stop.

Deferred Tax Liability (DTL) — you've paid less tax now than your book profit suggests, and will pay more later

Classic example — depreciation. In the early years of an asset's life, tax depreciation (accelerated WDV rates under Section 32) usually exceeds book depreciation (spread more evenly under Schedule II). This means taxable income is lower than book profit in early years purely because of this timing difference — the company pays less cash tax now than the book profit would suggest. But total depreciation claimed over the asset's life is capped at its cost either way, so in later years, once tax depreciation runs out faster than book depreciation, taxable income will be higher than book profit, and the company will pay more tax than the book tax expense in those later years. The company effectively owes tax back to the government in the future — that obligation is recognised today as a Deferred Tax Liability.

Deferred Tax Asset (DTA) — you've paid more tax now than your book profit suggests, and will pay less later

Classic example — the unpaid GST and gratuity provision in our worked example. The ₹2.5 lakh GST and ₹4 lakh gratuity provision were added back this year because they haven't been paid yet — the company pays tax on them now even though the expense already sits in this year's books. But once the GST is paid next year (or the gratuity is actually disbursed or funded), that amount becomes tax-deductible in that future year, reducing the tax payable then. The company has effectively prepaid tax on an expense it will get credit for later — that future tax benefit is recognised today as a Deferred Tax Asset. A DTA also commonly arises from carried-forward business losses or unabsorbed depreciation, to the extent there is reasonable/virtual certainty of future taxable profits against which they can be set off.

Continuing the worked example

Say the depreciation timing difference for the year (tax depreciation ₹22,00,000 minus book depreciation ₹18,00,000 = ₹4,00,000 higher tax deduction this year) and the GST/gratuity timing differences (₹2,50,000 + ₹4,00,000 = ₹6,50,000 disallowed this year, deductible later) are the only temporary differences, at a 25% + surcharge + cess effective rate of roughly 27.82%:

Item	Temporary difference	Nature	Deferred tax impact @ ~27.82%
Depreciation (tax > book this year)	₹4,00,000	Will reverse — book depreciation exceeds tax depreciation in later years	Deferred Tax Liability of ~₹1,11,280
GST + gratuity provision (disallowed this year)	₹6,50,000	Will reverse — deductible for tax once paid	Deferred Tax Asset of ~₹1,80,830

Under AS 22 / Ind AS 12, DTA and DTL on different items are generally offset against each other (where they relate to taxes levied by the same authority and there's a legal right of set-off) and shown net on the balance sheet — here, a net Deferred Tax Asset of roughly ₹69,550. The movement in this net DTA/DTL balance from one year to the next is what gets recognised as "Deferred Tax" in the P&L, adjusting the current year's tax charge so that the total tax expense reported (current tax + deferred tax) properly matches the accounting profit for the year, not just the year's cash tax outflow.

Deferred tax and MAT credit are not the same thing

It's easy to conflate the two, but they're separate mechanisms. MAT credit under Section 115JAA arises specifically when a company pays tax under the MAT provisions (because 15% of book profit exceeds tax computed under normal provisions) — the excess MAT paid over normal tax is available as a credit to be set off against normal tax in future years (subject to a time limit), and this MAT credit entitlement is itself recognised as an asset in the books, separately from DTA/DTL. Companies that have opted for Section 115BAA or 115BAB are outside MAT entirely — for them, MAT credit is not a live question, though ordinary DTA/DTL on timing differences (depreciation, provisions, etc.) still applies as normal.

Frequently Asked Questions

Why isn't a company's tax simply P&L profit multiplied by the tax rate?

Because book profit is computed under accounting standards to show a true and fair view of performance, while taxable income is computed under the Income-tax Act, which allows, disallows, or times deductions differently — e.g. disallowing unpaid statutory dues, using its own depreciation rates, and refusing deductions for CSR spend or penalties.

What is the difference between a permanent difference and a timing difference?

A timing difference reverses in a future year — the item eventually gets tax treatment consistent with the books, just in a different period (e.g. depreciation, unpaid statutory dues). A permanent difference never reverses — the item is simply never deductible for tax, in any year (e.g. CSR expenditure, penalties, income tax itself). Only timing differences create Deferred Tax Assets or Liabilities.

Is a Deferred Tax Asset the same as a refund the company will get?

No. A DTA is not a cash refund claim against the tax department. It represents a future reduction in tax payable, recognised in the company's own books because an expense already booked will become tax-deductible in a later year (or because of carried-forward losses that can offset future taxable profit).

Does every company have to recognise deferred tax?

Companies preparing financial statements under Accounting Standards (AS 22) or Ind AS (Ind AS 12) are required to recognise deferred tax. A Deferred Tax Asset arising from unabsorbed depreciation or carried-forward losses is recognised only if there is virtual certainty (AS 22, for entities with no unabsorbed depreciation/losses) or reasonable certainty of future taxable income to realise it.

Does choosing Section 115BAA or 115BAB avoid deferred tax altogether?

No. It removes MAT applicability, but ordinary timing differences — like the gap between book and tax depreciation, or provisions disallowed under Section 43B — still exist and still require DTA/DTL to be recognised in the books.

What's the difference between MAT credit and a Deferred Tax Asset?

MAT credit under Section 115JAA is the excess tax paid under the MAT provisions (15% of book profit) over the tax computed under normal provisions, available for set-off in future years when normal tax exceeds MAT. It's tracked and recognised separately from DTA/DTL, which arise from ordinary timing differences between book and taxable income.

Can a company have both a DTA and a DTL at the same time?

Yes — different timing differences can point in opposite directions (as in the worked example above, where depreciation creates a DTL and the unpaid provisions create a DTA). Where the conditions for offset are met, these are shown net on the balance sheet as either a net Deferred Tax Asset or a net Deferred Tax Liability.

Does MAT apply to every company on the normal tax regime?

MAT under Section 115JB applies to companies on normal provisions whenever tax computed under normal provisions is less than 15% of book profit (book profit here being a separately adjusted figure, not identical to either accounting profit or taxable income). Companies opting for Section 115BAA or 115BAB are excluded from MAT altogether.

Between tracking every Section 43B item, reconciling book vs tax depreciation asset-block by asset-block, and working out the resulting DTA/DTL movement correctly every year, a manual tax computation is one of the easiest places for errors to slip through. assureOffice's Financial Builder pulls the trial balance straight from Tally, builds the P&L and Balance Sheet, and carries the numbers into a structured tax computation — already tested and used by hundreds of practising professionals.