Interest Computation Under the Look-Back Method for Completed Long-Term Contracts

Use the California Tax Form Calculator California Tax Form 3834 as a stand alone tax form calculator to quickly calculate specific amounts for your 2026 California state tax return. Alternatively, you can use one of our Combined Federal and State Tax Estimators to quickly calculate your salary, tax, and take-home pay.

Interest Computation Under the Look-Back Method for Completed Long-Term Contracts
Individual Estate Trust C corporation S corporation Partnership Limited liability company (LLC) Exempt organization Other
If you owned an interest in a pass-through entity (S corporation, estate, trust, partnership, or LLC treated as a partnership) that holds one or more long-term contracts to which this interest computation relates, enter the name and identification number of the entity. Attach a schedule if there is more than one entity.
Check this box if more than three prior years are involved. Attach additional form(s) FTB 3834 as needed. See General Information J, Miscellaneous.
Part I Regular Method		Filing year	Redetermination years		(c) Totals add columns (a) and (b)
1	Taxable income (loss) or net income (loss) for state purposes for the prior year(s) shown on tax return (or as previously adjusted) before net operating loss. If you were required to file form FTB 3834 for an earlier contract completion year, enter adjusted taxable income or net income for state purposes for the prior year(s) from form FTB 3834, line 3, for the most recent contract completion year that affects the prior year(s). Attach a copy of the prior year(s) form FTB 3834 to this form	Year ended mm yyyy	(a) Year ended mm yyyy	(b) Year ended mm yyyy	(c) Totals add columns (a) and (b)
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2	Adjustment to income to reflect the difference between: (a) the amount of regular taxable income required to be allocated to postFebruary 1986 contracts completed or adjusted during the taxable year based on the actual contract price and costs; and (b) the amount of income reported for such contracts based on estimated contract price and costs. See instructions
3	Adjusted taxable or net income for look-back purposes. Combine line 1 and line 2
4	Tax on line 3 amount using tax rates in effect for the prior year(s). See instructions
5	Tax shown on return (or as previously adjusted) for the prior year(s). See instructions. If you were required to file form FTB 3834 for an earlier contract completion year, enter the amount required to be reported on form FTB 3834, line 4, for the most recent contract completion year that affects the prior year(s)
6	Increase (or decrease) in tax for the prior year(s) on which interest is due (or is to be refunded). Subtract line 5 from line 4
7	Interest due on increase in tax, if any, shown on line 6. See instructions
8	Interest to be refunded on decrease in tax, if any, shown on line 6. See instructions
9	INTEREST TO BE REFUNDED TO YOU – If line 8, column (c) exceeds line 7, column (c), enter the excess. See instructions
10	INTEREST YOU OWE – If line 7, column (c) exceeds line 8, column (c), enter the excess. See instructions
Part II Simplified Marginal Impact Method
		Date of each prior year to which interest computation relates			(d) Totals add columns (a), (b), and (c)
1	Adjustment to regular taxable income to reflect the difference between (a) the amount of income required to be allocated for post-February 1986 contracts completed or adjusted during the taxable year based on actual contract price and costs; and (b) the amount of income reported for such contracts based on estimated contract price and costs. See instructions	(a) Year ended mm yyyy	(b) Year ended mm yyyy	(c) Year ended mm yyyy	(d) Totals add columns (a), (b), and (c)
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2	Increase (or decrease) in regular tax for prior year(s). Multiply line 1 in each column by the applicable regular tax rate. See instructions. For prior years beginning before 1987, skip line 3 and line 4 and enter on line 5 the amount from line 2
3	Adjustment to alternative minimum taxable income to reflect the difference between: (a) the amount of income required to be allocated for post-February 1986 contracts completed or adjusted during the taxable year based on actual contract price and costs; and (b) the amount of income reported for such contracts based on estimated contract price and costs. See instructions
4	Increase (or decrease) in alternative minimum tax (AMT) for prior year(s). Multiply line 3 in each column by the applicable AMT rate. See instructions
5	Enter the amount from line 2 or line 4, whichever is larger. See instructions if either amount is negative. Pass-through entities (except S corporations): Skip line 6 and enter on line 7 the amount from line 5. S corporations: See General Information I, S Corporations
6	Overpayment ceiling. For each column in which line 5 is a negative number, enter your total tax liability for the prior year, as adjusted for past applications of the look-back method, and after net operating losses, capital losses, and credit carryovers to that year. For each column in which line 5 is a positive number, leave line 6 blank and enter on line 7 the amount from line 5
7	Increase (or decrease) in tax for the prior year(s) on which interest is due (or is to be refunded). Enter the amount from line 5 or line 6, whichever is smaller. Treat both numbers as positive when making this comparison, but enter the amount as a negative number
8	Interest due on increase in tax, if any, shown on line 7. See the instructions for Part I, line 7 and line 8
9	Interest to be refunded on decrease in tax, if any, shown on line 7. See the instructions for Part I, line 7 and line 8
10	INTEREST TO BE REFUNDED TO YOU – If line 9, column (d) exceeds line 8, column (d), enter the excess. See the instructions for Part I, line 9
11	INTEREST YOU OWE – If line 8, column (d) exceeds line 9, column (d), enter the excess. See the instructions for Part I, line 10

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Frequently Asked Questions

How does community property affect my CA return?

Married/RDP filers may have community property allocation rules; see CA guidance.

Are employer retirement contributions taxed by CA?

Pre-tax 401(k)/403(b) contributions reduce federal and generally CA taxable wages.

Is there a separate Medicare surtax in CA?

Additional Medicare is federal; California PIT is separate and applies via its own brackets/credits.

Does CA tax out-of-state remote work?

CA generally taxes income earned while working in CA; non-CA work may be non-CA source—track days/location.

Can I deduct mortgage interest in CA?

Often yes, subject to CA limits/adjustments; compare standard vs itemized for CA.

Important Notes

All calculations are estimates for guidance only. Always review your return and consider professional advice when submitting official filings.