What does a tax return actually show?

Far more than the refund or balance due. A complete return is a map of your financial year:

• Form 1040: total income, adjusted gross income, taxable income, total tax, and what you paid through withholding and estimated payments. Together these show your marginal bracket, the rate every strategy is measured against.

• W-2s (if included with your copy): wages, and in box 12, how much you deferred into your 401(k).

• Schedule A: whether you itemize, and how close you are to the standard deduction.

• Schedule B: interest and dividend income.

• Schedule C: self-employment or side-business income and expenses.

• Schedule D and Form 8949: capital gains and losses, including any loss carryover into next year.

• Schedule E: rental income, depreciation, and income from partnerships and S-Corps (K-1s).

• Form 4562: the depreciation you're taking, and on what.

• Form 8606: nondeductible IRA contributions, which matter for a backdoor Roth.

• Form 8995: the qualified business income deduction, if you have pass-through income.

• Form 2210: whether you owed an underpayment penalty.

• Forms 6251 and 8960: whether the alternative minimum tax or net investment income tax applied.

• Your state return: state rate, credits, and anything the state treats differently.

What can an analysis find from last year's return?

Most strategies show up as a gap between what the return shows and what the tax code allows. A few examples:

• A high marginal rate with room left in your 401(k): every extra dollar deferred saves you that rate.

• Rental property with only standard depreciation: a candidate for a cost segregation study, including a look-back on a property you already own.

• Healthy Schedule C profit taxed as a sole proprietor: a candidate for an S-Corp analysis.

• An underpayment penalty on Form 2210: usually a withholding problem, often from RSUs, with a clear fix.

• Itemized deductions just above or below the standard deduction: a candidate for timing strategies.

• A capital loss carryover: a tool you can plan future gains around.

• Form 8606 and IRA activity on the return: a starting point for checking whether a backdoor Roth would trigger tax under the pro-rata rule. We confirm your year-end IRA balances before recommending one.

Because your income sources and structure usually carry over from year to year, these findings tend to still apply.

What can't a prior-year return show?

Anything that changed after you filed:

• A new job, raise, or bonus

• New equity grants, vests, or exercises

• A home purchase or sale

• Marriage, divorce, or a new child

• A new business or rental property

• A sale or liquidity event you're planning

That's why the analysis is a starting point, not a final plan. If you become a client, we update it with everything specific to your current year.

Which return should I send?

Your most recent filed return, complete: the full federal return with every schedule and form, plus your state return. A PDF from your preparer or tax software works. The more complete the copy, the more the analysis can find.

How does Gambit use it?

It's the only document the Tax Opportunity Report needs. We evaluate your return against 100+ IRS-approved strategies and send you your tax profile, compliance flags, missed strategies with estimated savings, and a fixed-fee quote in 1 to 3 business days. See an annotated example.

Worried about sending it? Here's how we protect your return.

Frequently asked questions

Can you do tax planning from a prior-year return?

Yes, for most of it. Last year's return shows your income sources, marginal rate, deductions, carryforwards, and penalties, which is where most planning opportunities show up. Current-year changes are added once you're a client.

Why don't you need my current-year documents first?

Because the structure of your finances rarely changes completely in a year. The return you already filed shows enough to find real opportunities and put numbers on them. We ask for current-year documents only if you decide to work with us.

What if my income changed a lot this year?

The report still shows where you stood and what applied. Tell us what changed, and we'll factor it in when we build your strategy.

Do I need to send my W-2s and 1099s too?

Not for the report. The return itself is enough. If your copy includes W-2s, that helps, since box 12 shows your 401(k) deferrals.

How far back should the return be?

Your most recent filed year. Older returns are useful mainly for finding amendments, which are generally limited to 3 years from filing or 2 years from paying the tax.

About the author

Brian Thomas, EA is a co-founder of Gambit. He is an IRS Enrolled Agent, a California Tax Education Council registered tax preparer (CTEC #A355130), and the President of the California Chapter of the National Association of Tax Professionals, and holds an MBA from UCLA. Meet the Gambit team.

Last updated: September 30, 2026