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Last updated: October 5, 2026

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1099-DA Basis-Gap Calculator

Form 1099-DA reports gross proceeds of a reportable broker-effected disposition. Basis reporting was optional for 2025 sales; later, a custodial broker generally must report basis only for units it acquired in the customer's account on or after January 1, 2026. Missing basis does not itself make the full proceeds taxable gain. Reconcile the actual form and records; for a capital-asset disposition on Form 8949 and Schedule D, this tool illustrates the potential difference if $0 basis were used.

If you do not know an input, check your records before relying on a result. A blank is not a confirmed zero.

Gross proceeds (from 1099-DA)Your actual cost basisHolding periodFederal LTCG bracket

I’m a New Jersey resident (optionally add a user-selected NJ marginal-rate sensitivity)I understand this is an illustrative estimate, not bracket math - it applies a single flat combined rate and ignores other income, netting, NIIT/AMT, and deductions. It is not tax advice.

Check the box above to view your illustrative estimate.

Estimate only - not tax advice. This calculator uses simplified illustrative rates and applies them to the full amount; it ignores other income, netting, AMT/NIIT, deductions, and actual bracket math. The optional NJ amount uses a marginal rate you select as a sensitivity input, not a default or flat-rate proxy. New Jersey taxes capital gains at ordinary-income rates under filing-status-specific graduated schedules and has its own loss-netting rules, so your NJ result may differ materially. Your real result depends on your full return. See our 1099-DA cost-basis review and consult a CPA before relying on these figures.

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Tax advice disclaimer: This material is for general educational information only and is not legal, tax, or accounting advice for your specific facts. A CPA-client relationship is formed only through a signed engagement letter.