Corporate Tax Return Preparation Checklist

Pull the current-year engagement letter from Practice Ignition or TaxDome. Scope must explicitly cover the federal return, named state returns, and any 7004 extension. Prior-year letters do not roll forward automatically — a missing current-year letter is a Circular 230 problem if the return is filed.

Confirm the entity classification against the prior-year return and any Form 2553 / 8832 elections in the permanent file. C-corps file Form 1120 by April 15; S-corps file Form 1120-S by March 15. A late-March discovery that the client revoked S-status mid-year is the kind of surprise that blows the deadline.

Confirm the registered agent and HQ address haven't changed since the prior year. Pull a 50-state revenue summary to flag any new economic-nexus states crossing $100K or 200 transactions — those become new state filings this year.

Export the post-close trial balance from QuickBooks Online, Xero, or Sage Intacct as of the fiscal year-end. Import into the workpaper file (CCH Engagement, Caseware, or your firm's templated workbook). Confirm the period is locked in the GL before importing — re-imports after AJEs cause version drift.

Tie every bank and credit-card account to the December (or fiscal year-end) statement. Investigate uncleared items older than 30 days and any $1,000+ reconciling items. Stale outstanding checks need a written-off entry before the books are tax-ready.

Run the A/R and A/P aging reports as of year-end and tie totals to the GL control accounts. Document any variance on the lead schedule. Bad-debt write-offs identified here become a Schedule M-1 reconciling item if the books are accrual but the return is cash-basis.

Update the depreciation schedule for current-year additions, dispositions, and impairments. Tie ending accumulated depreciation to the GL. Book vs. tax depreciation differences feed Form 4562 and the M-1 reconciliation downstream.

Set the close date and password in QBO / Xero / Sage so the client can't post into the prior period after tax work begins. Mid-prep edits are the most common cause of returns disagreeing with books at partner review.

Send the prepared-by-client request list via Suralink, TaxDome, or Liscio with a hard internal deadline 30 days before the filing date. Track weekly with the controller — half-complete PBC at fieldwork start is the #1 cause of fee overruns.

Pull December statements for every operating, savings, and brokerage account, plus 1099-INT, 1099-DIV, and 1099-B from each broker. Cross-check against the GL — undisclosed accounts surface here when interest income doesn't match.

Collect Q1–Q4 941s, the 940, all state UI / withholding returns, and the W-3 totals from Gusto / ADP / Paychex. Wages on the W-3 should tie to wages on the 941s and to GL salary accounts; a variance usually means a missing fringe-benefit accrual.

Confirm 1099s were filed by January 31 for every non-corporate vendor paid more than $600 for services. Missing W-9s in the vendor master mean 1099 obligations that quietly slipped — the IRS penalty is per form per year.

Decide with the partner whether the return will be filed by the original due date or extended on Form 7004. Extension extends time to file, NOT time to pay — any expected balance due must still be remitted with the 7004.

Reconcile book net income to taxable income line-by-line: meals disallowance, fines/penalties, tax-exempt interest, federal income tax expense, depreciation differences, accrual-to-cash adjustments. Use Schedule M-3 if total assets are $10M+.

Confirm the COA separates 100% deductible categories (employee snacks, office events) from 50% deductible business meals. Entertainment remains fully nondeductible post-TCJA. A single "Meals & Entertainment" account dumped into a 50% adjustment overstates the disallowance.

Apply Section 179 expensing within the annual cap and taxable-income limitation, then layer bonus depreciation on remaining qualifying property at the current-year phase-down percentage. State conformity varies — many states decouple from bonus and require an addback.

Build the sales, payroll, and property factors for each nexus state. Sourcing rules differ — most states use market-based sourcing for services, a few still use cost-of-performance. Document the source data so the workpaper survives a state audit.

Required for every S-corp shareholder claiming losses, receiving distributions, or with loan repayments. Roll basis from prior-year 7203, add current-year income/contributions, subtract distributions and losses. Without a current 7203, K-1 losses are at risk in an exam.

E-file Form 7004 by the original due date with a reasonable estimate of tax due paid via EFTPS. An extension with no payment when balance is owed still triggers failure-to-pay penalties even though late-filing penalty is avoided.

Roll the prior-year file forward in UltraTax, Lacerte, ProSystem fx, or Drake. Import the trial balance via the GL bridge, then post each M-1 adjustment as a tax-only entry so book-to-tax differences are transparent in the workpaper.

Generate every state return where the entity has filing nexus, including PTET elections (NY, CA, NJ and ~30 others) where they're advantageous. Don't forget local returns — Philadelphia BIRT, NYC GCT, Detroit, Portland Metro, etc. ride alongside the state.

Run the diagnostics report and resolve every red (critical) and yellow (warning) item. Critical diagnostics will reject at e-file; warnings often surface real issues — basis missing, EIN mismatch, K-1 percentages not summing to 100.

Pull the current-year IRS account transcript via TDS or Canopy and tie posted estimated payments to what the client claims they paid. Misapplied or missing payments at the IRS but credited on the books cause balance-due notices weeks after filing.

Block a 60-minute slot with the signing partner once diagnostics are clear. Bring the trial balance, M-1 reconciliation, depreciation schedule, and any unresolved technical questions. Avoid the 48-hours-before-deadline scramble.

Resolve every review note in the workpaper file with a written response. Re-run diagnostics after substantive changes — late edits often introduce new criticals. Leave the review-note thread in the file for permanent documentation.

Deliver the signature-ready PDF via TaxDome, DocuSign, or Liscio. Form 8879-C (or 8879-S) authorizes e-filing and must be signed before transmission — never e-file on a verbal go-ahead.

Transmit through the tax software and monitor for IRS / state acknowledgements. A return is not filed until the ACK shows accepted — submitted returns can reject for trivial reasons (PIN mismatch, dependent SSN issue) and need re-transmission within the perfection period.

Archive the workpaper file to the permanent folder, update the carryforward schedules (NOL, basis, credits, AMT), and roll forward to the next year's file in the tax software. Capture lessons-learned in the engagement notes for next season.