Corporate AMT Calculator

Calculator Inputs

Enter reductions as negative values where appropriate. This estimator is designed around U.S. corporate CAMT style calculations and is best used for planning.

Company Name

Tax Year

3-Year Average AFSI (General Test)

Used for the general $1 billion threshold test.

3-Year Average AFSI (FPMG $100M Test)

Needed when the corporation is in a foreign-parented multinational group.

Corporation is part of an FPMG

Financial Net Income

Period Mismatch Adjustment

Nonconsolidated Entity Adjustment

CFC Adjustment

Foreign Non-ECI Adjustment

Use a negative amount to remove non-U.S. effectively connected income.

Tax Expense Adjustment

Depreciation / Amortization Adjustment

Pension / Benefit Plan Adjustment

Other AFSI Adjustments

FSNOL Carryover Available

CAMT Foreign Tax Credit

Regular Tax Liability

Use regular tax after relevant foreign tax credit reductions.

BEAT Liability

Prior-Year Minimum Tax Credit

Example Data Table

Metric	Example Value
Company	Demo Manufacturing Inc.
Tax Year	2026
3-Year Average AFSI (General Test)	$1,350,000,000.00
Financial Net Income	$420,000,000.00
Total Adjustments Before FSNOL	$42,000,000.00
Base AFSI	$462,000,000.00
FSNOL Carryover Used	$60,000,000.00
AFSI After FSNOL	$402,000,000.00
Tentative Tax Before FTC	$60,300,000.00
CAMT FTC Used	$9,000,000.00
Tentative Minimum Tax	$51,300,000.00
Regular Tax + BEAT	$43,000,000.00
Estimated CAMT Due	$8,300,000.00
Estimated Net Tax After Prior-Year Credit	$45,300,000.00

Formula Used

1) Base AFSI
Base AFSI = Financial Net Income + Period Adjustment + Nonconsolidated Adjustment + CFC Adjustment + Foreign Non-ECI Adjustment + Tax Expense Adjustment + Depreciation Adjustment + Pension Adjustment + Other Adjustments

2) FSNOL Limit
FSNOL Limit = 80% × max(Base AFSI, 0)

3) FSNOL Used
FSNOL Used = lesser of FSNOL Carryover Available and FSNOL Limit

4) AFSI After FSNOL
AFSI After FSNOL = Base AFSI − FSNOL Used

5) Tentative Minimum Tax
Tentative Tax Before FTC = 15% × max(AFSI After FSNOL, 0)
Tentative Minimum Tax = Tentative Tax Before FTC − CAMT FTC

6) Estimated CAMT Due
Estimated CAMT Due = max(Tentative Minimum Tax − (Regular Tax Liability + BEAT Liability), 0)

7) Estimated Net Tax After Prior-Year Credit
Net Estimated Tax After Credit = max((Regular Tax + BEAT + CAMT Due) − Prior-Year Minimum Tax Credit Used, 0)

How to Use This Calculator

Enter the corporation name and tax year for your planning file.
Fill in the 3-year average AFSI to test whether the corporation falls into the CAMT regime.
Add financial statement net income and the adjustments needed to estimate AFSI for the year.
Enter available FSNOL carryover, CAMT foreign tax credit, regular tax, and any BEAT amount.
Press the calculate button to show base AFSI, tentative minimum tax, and estimated CAMT due.
Use CSV or PDF export to save a planning snapshot for internal review.

Important Notes

This estimator intentionally simplifies some real filing issues, including highly technical adjustments, elections, group mechanics, and foreign tax credit details.

The prior-year minimum tax credit is shown as a planning reduction to total estimated tax. Actual credit usage depends on the filing position and supporting forms.

Always compare this estimate with your current tax workpapers, Form 4626 approach, and professional advice before filing.

FAQs

1. What does this calculator estimate?

It estimates corporate alternative minimum tax using AFSI-style inputs, FSNOL limits, credits, regular tax, and BEAT. It is mainly for planning and internal review.

2. Who should use this tool?

Tax teams, controllers, finance managers, and advisors can use it to test whether a large corporation may owe CAMT under different scenarios.

3. What is AFSI in simple terms?

AFSI starts from applicable financial statement income and then applies tax-law adjustments. It is a book-income-based measure used for corporate minimum tax testing.

4. Why is there an FSNOL limit?

The calculator limits FSNOL use to 80% of positive AFSI, which prevents the loss deduction from eliminating too much CAMT base in one year.

5. What happens if regular tax already exceeds tentative minimum tax?

Then estimated CAMT due becomes zero. The corporation may still be within the regime, but current-year CAMT would not add extra tax.

6. Should I include negative adjustments?

Yes. Use negative values whenever an adjustment reduces AFSI, such as removing non-ECI income or reflecting a favorable depreciation adjustment.

7. Does this replace Form 4626 workpapers?

No. It is a structured estimator. Filing still requires detailed support, final instructions, and review of any elections or interim guidance relied upon.

8. What do the export buttons save?

CSV exports the full input and result dataset. PDF exports a concise printable summary with company details, key inputs, and computed tax outputs.