18.3 C Corporation NOLs, Capital Losses, Credits, and Tax
Key Takeaways
- Post-2017 C corporation NOLs generally cannot be carried back, carry forward indefinitely, and may offset only 80 percent of taxable income computed before the NOL deduction.
- A $100,000 NOL from 2024 applied against $60,000 of 2026 taxable income uses $48,000; $12,000 remains taxable and $52,000 of NOL carries forward.
- Corporate capital losses offset only capital gains and use a 3-year carryback / 5-year carryforward — a different statute from §172.
- General business credits reduce tax, not taxable income, and are limited so they cannot generally drive tax to zero.
- A C corporation that expects tax of $500 or more pays estimated tax in four installments due the 15th day of the 4th, 6th, 9th, and 12th months of the tax year.
18.3 C Corporation NOLs, Capital Losses, Credits, and Tax
REG Area V, Group B, Topic 1 continues past taxable income: calculate the current-year net operating or capital loss and the limitations on use in the current year, calculate the credits allowable as a reduction to tax, and arrive at tax due. The 21 percent rate from Section 18.2 applies to whatever taxable income survives the NOL limitation.
Net operating losses — §172 after TCJA
For NOLs arising in tax years beginning after December 31, 2017 — the TCJA rule still in force for routine REG facts, and not rewritten by OBBBA for C corporations:
- No carryback, generally. The CARES Act two- and five-year carrybacks were temporary and have expired for current-year losses.
- Indefinite carryforward.
- The deduction in a carry year cannot exceed 80 percent of taxable income computed without the NOL deduction (and without certain other specified deductions).
Pre-2018 NOLs, if they still appear in a fact pattern, keep their old two-year carryback / 20-year carryforward and can offset 100 percent of taxable income. REG stems that say a 2024 NOL or a post-2017 NOL want the 80 percent / no carryback / indefinite rule.
The 80 percent limit is applied to taxable income before the NOL, not to tax and not to book income. Section 382 ownership-change limits are a TCP-level overlay unless the Blueprint facts give an ownership change; do not invent a §382 haircut on a clean REG stem.
Worked: 2024 NOL $100,000, 2026 taxable income $60,000
Facts. Calendar-year C corporation. A $100,000 NOL arose in 2024. In 2026, taxable income before the NOL deduction is $60,000. No pre-2018 NOL. No other limitations.
Limit. 80% × $60,000 = $48,000.
| Item | Amount |
|---|---|
| 2026 taxable income before NOL | $60,000 |
| NOL used in 2026 | $48,000 |
| Taxable income after NOL | $12,000 |
| NOL remaining to carry forward | $52,000 |
| Tentative tax at 21% | $12,000 × 21% = $2,520 |
Using the entire $60,000 of income — or the entire $100,000 NOL — is the usual miss. The $12,000 that remains is taxable. The unused $52,000 does not expire; it continues forward, still subject to 80 percent in later years. There is no carryback of the 2024 loss into 2023 or 2022.
Capital losses contrasted
| Feature | Post-2017 NOL (§172) | Corporate capital loss (§1212(a)) |
|---|---|---|
| What it offsets | Taxable income, after the 80% cap | Capital gains only |
| Carryback | Generally none | 3 years |
| Carryforward | Indefinite | 5 years |
| Ordinary offset | No | No $3,000 ordinary allowance |
A net capital loss is not an NOL. Do not run a capital-loss leftover through the 80 percent NOL formula, and do not carry an NOL back three years because that is the capital-loss clock. The two limitations can appear in the same year: a corporation can have capital-gain netting on Schedule D and a separate §172 NOL against remaining taxable income.
Credits and tax
Regular tax is 21 percent of taxable income after the allowed NOL. General business credits (the §38 cluster — research, work opportunity, employer credits, and others aggregated on Form 3800) then reduce that tax. They do not reduce taxable income.
Credits are income-tax limited. Under §38(c), the general business credit cannot reduce tax below a statutory floor: net income tax minus the greater of tentative minimum tax or 25 percent of net regular tax liability above $25,000. Unused amounts generally carry back one year and forward 20 years. REG will not ask you to memorize every credit's eligibility grid. It will ask whether credits reduce tax (they do) and whether they can zero out a large tax (generally no — a floor remains).
The corporate alternative minimum tax of former §55 is not the routine REG computation. Very large corporations may face the book-income corporate alternative minimum tax; that is not the default 21 percent computation on a mid-size Form 1120.
Penalty taxes on unreasonable accumulations of earnings (accumulated earnings tax) and on certain closely held personal holding companies still exist as anti-avoidance overlays; they are not the routine REG taxable-income computation.
Estimated tax
A C corporation that expects tax of $500 or more must pay estimated tax. Installments are due the 15th day of the 4th, 6th, 9th, and 12th months of the tax year (April 15, June 15, September 15, and December 15 for a calendar-year corporation). Safe harbors are 100 percent of the current-year tax or, if the prior year was a full 12 months and showed a tax liability, 100 percent of the prior-year tax. A large corporation (taxable income of $1 million or more in any of the three preceding years) may use the prior-year safe harbor only for the first installment. Underpayment penalty is computed on Form 2220.
Individual estimated-tax safe harbors (90 / 100 / 110 percent bands tied to AGI) are Section 17.3; do not import them onto Form 1120. A corporation does not use a 90 percent current-year individual harbor.
A C corporation has a $100,000 NOL from 2024 and $60,000 of taxable income in 2026 before the NOL. No pre-2018 NOL applies. How much of the NOL is used in 2026?
Which statement correctly contrasts a post-2017 C corporation NOL with a C corporation capital loss?
Which statement correctly describes C corporation estimated tax?