A good tax prep checklist does two jobs. It tells clients exactly which documents to send, and it tells your firm what must be ready before the first return comes in. This guide covers both for the 2027 filing season (tax year 2026 returns).
Key takeaways
- Every client needs the basics: prior-year return, IDs and SSNs, all W-2s and 1099s, bank and brokerage statements, and records of estimated payments.
- Business clients need extra, entity-specific documents: officer W-2s and basis worksheets for S corporations, capital accounts for partnerships, mileage and home office records for Schedule C filers.
- Tax year 2026 brings real changes from the One Big Beautiful Bill Act: a $2,000 threshold for Form 1099-NEC, a $40,400 SALT cap, new deductions for tips, overtime and seniors, and a charitable deduction for non-itemizers.
- Key 2027 dates: February 1 (W-2s and 1099-NEC), March 15 (S corporations and partnerships), April 15 (individuals and C corporations).
- Firms should renew PTINs by December 31, update their Written Information Security Plan, and send client organizers in early January.
Picture the usual February. Your inbox fills with half-complete uploads, staff chase missing K-1s, and preparers wait instead of preparing. Most delays have nothing to do with complex tax law. They come from missing information and an unready process.
This checklist fixes both. Part 1 is the client-facing document list, split by return type, which you can send to clients as-is. Parts 2 to 5 cover the law changes, internal readiness, deadlines and client communication your firm needs in place before January.
Part 1: Client Tax Prep Checklist (What Every Client Must Send)
These documents apply to every client, individual or business. Send this list with your client organizer in early January and ask clients to upload everything through your secure portal.
Personal and identity information
- Prior-year federal and state tax returns
- Full legal names, Social Security numbers (or ITINs) and dates of birth for the taxpayer, spouse and dependents
- Government-issued photo ID for identity verification
- Current address, phone and email; note any move during the year
- Bank routing and account numbers for direct deposit or debit
- IRS Identity Protection PIN (IP PIN), if one was issued
- Any IRS or state notices received during the year
Income documents
- Form W-2 from every employer
- Form 1099-NEC and 1099-MISC (contract and miscellaneous income)
- Form 1099-K from payment apps and marketplaces (PayPal, Stripe, Square, Etsy)
- Form 1099-INT and 1099-DIV (interest and dividends)
- Form 1099-B and year-end brokerage statements with cost basis
- Cryptocurrency and digital asset transaction reports
- Form 1099-R (pension, IRA and retirement distributions)
- Form SSA-1099 (Social Security benefits)
- Form 1099-G (unemployment or state refunds)
- Schedule K-1s from partnerships, S corporations, trusts and estates
- Rental property income and expense records
- Records of tips and overtime pay (needed for the new deductions)
- Alimony received (divorce agreements finalized before 2019)
- Gambling winnings (Form W-2G) and losses
Deduction and credit documents
- Form 1098 (mortgage interest) and property tax statements
- State and local income or sales tax paid
- Charitable donation receipts, cash and non-cash
- Medical and dental expenses
- Form 1098-T (tuition) and Form 1098-E (student loan interest)
- Child and dependent care expenses with provider name and EIN or SSN
- Retirement contributions (IRA, Roth IRA, SEP, Solo 401(k))
- Form 5498-SA and 1099-SA (HSA contributions and distributions)
- Form 1095-A if insured through the Health Insurance Marketplace
- Car loan interest statement and vehicle VIN (new vehicle loan interest deduction)
- Records of cash gifts to charity, even if the client does not itemize (new $1,000 / $2,000 deduction)
Tax payments
- Federal and state estimated tax payments, with dates and amounts
- Prior-year overpayment applied to the current year
- Any extension payments made
Business Tax Prep Checklist by Entity Type
Business returns need the universal documents above plus the items below. Match the list to the return you file.
All business clients
- EIN confirmation letter (CP 575 or 147C)
- Formation documents: articles, operating or partnership agreement, bylaws
- Year-end profit and loss statement and balance sheet
- Bank, credit card and loan statements for all 12 months, reconciled
- General ledger or accounting software access (QuickBooks, Xero)
- Fixed asset purchases and disposals, with dates and cost
- Prior-year depreciation schedules
- Payroll reports, Forms 941 or 944, Form 940 and state payroll filings
- Forms 1099-NEC issued to contractors, with W-9s on file
- Inventory counts at year-end, if applicable
- Business insurance, rent and lease agreements
Sole proprietors and single-member LLCs (Schedule C)
- Gross receipts: invoices, sales reports, 1099-NEC and 1099-K forms received
- Expense receipts sorted by category
- Mileage log: date, destination, business purpose, miles
- Home office square footage plus rent or mortgage interest, utilities and insurance
- Self-employed health insurance premiums
- SEP-IRA, Solo 401(k) or SIMPLE IRA contributions
S corporations (Form 1120-S)
- Shareholder names, SSNs and ownership percentages
- W-2s for shareholder-employees and support for reasonable compensation
- Health insurance paid for 2%+ shareholders (must appear on their W-2)
- Distribution records by shareholder, with dates and amounts
- Shareholder stock and debt basis worksheets
- Shareholder loan documents (notes, interest, repayments)
- Board minutes and any stock transfers
Partnerships and multi-member LLCs (Form 1065)
- Partner names, SSNs or EINs and ownership percentages
- Partnership or operating agreement, including special allocations
- Capital account statements for each partner
- Partner contributions and distributions (cash and property)
- Guaranteed payments to partners
- Partner basis and at-risk worksheets
- Section 754 election documents, if any
C corporations (Form 1120)
- Officer compensation records
- Dividends paid, with dates and recipients
- Stock issuances, transfers and redemptions
- Net operating loss carryforward schedules
- Research and development and other credit documentation
- Corporate minutes and resolutions
Multi-state businesses
- Sales, payroll and property broken out by state
- Prior-year state returns for every state filed
- Nexus notes: why the business files in each state
Documents that come from third parties
| Document | Comes from | Expected by (2027) |
|---|---|---|
| W-2 | Employer | February 1 |
| 1099-NEC | Clients who paid $2,000 or more in 2026 | February 1 |
| 1099-INT, 1099-DIV, 1099-R, 1099-G | Banks, funds, retirement plans, states | February 1 |
| 1098, 1098-T, 1098-E | Lender, school, loan servicer | February 1 |
| 1099-K | Payment processors (over $20,000 and 200 transactions) | February 1 |
| 1099-B and consolidated brokerage 1099 | Brokerage | February 16, often later with corrections |
| 1095-A | Health Insurance Marketplace | February 1 |
| Schedule K-1 (1065, 1120-S) | Partnerships and S corporations | March 15, often later if extended |
| Schedule K-1 (1041) | Trusts and estates | April 15, often later if extended |
When January 31 falls on a weekend, the due date moves to the next business day. In 2027 it falls on a Sunday, so these forms are due Monday, February 1.
Part 2: 2026 Tax Law Changes to Build Into Your Checklist
The One Big Beautiful Bill Act (OBBBA), signed July 4, 2025, changes what you must collect for tax year 2026. Update your organizers and intake questions before you send them.
| Change | Tax year 2026 rule | What to collect or ask |
|---|---|---|
| Form 1099-NEC / 1099-MISC threshold | Rises to $2,000 (from $600) for payments made in 2026 | Remind clients that income is taxable even without a form; update vendor 1099 review |
| Form 1099-K threshold | Over $20,000 and over 200 transactions | Ask about all payment-app sales, not just those with a 1099-K |
| Standard deduction | $16,100 single; $32,200 married filing jointly; $24,150 head of household | Re-test itemize vs. standard for every client |
| SALT cap | $40,400 ($20,200 married filing separately), phased down at high incomes | Collect state income and property tax totals from former SALT-capped clients |
| No tax on tips | Deduct up to $25,000 of qualified tips (2025 to 2028) | Tip records and occupation |
| No tax on overtime | Deduct up to $12,500 ($25,000 joint) of qualified overtime premium (2025 to 2028) | Pay stubs or W-2 reporting of overtime |
| Senior deduction | Extra $6,000 per person age 65+, income-limited (2025 to 2028) | Dates of birth; MAGI |
| Car loan interest | Deduct up to $10,000 on loans for new US-assembled vehicles | Loan statement and VIN |
| Charitable giving | New $1,000 / $2,000 deduction for non-itemizers; 0.5% of AGI floor for itemizers | Cash gift receipts from all clients |
| Child Tax Credit | $2,200 per qualifying child | SSNs for children |
| Bonus depreciation | 100%, made permanent | Asset purchase dates and placed-in-service dates |
| QBI deduction | Made permanent | Pass-through income detail |
Sources: IRS 2026 inflation adjustments, IRS Form 1099-K fact sheet, IRS OBBB provisions hub. Confirm each figure against current IRS guidance before publishing.
The practical impact: more clients will benefit from new deductions, but only if your intake asks the right questions. Add yes/no questions on tips, overtime, car loans and cash donations to every individual organizer.
Part 3: CPA Firm Readiness Checklist
Perfect client documents still stall if your firm is not ready. Complete these items between October and early January.
Licensing and IRS credentials
- Renew every preparer’s PTIN. Renewal opens in mid-October and all PTINs expire on December 31. The 2026 fee was $18.75, and the IRS PTIN system now uses ID.me sign-in.
- Confirm your firm’s EFIN is active and the e-file application lists current principals and contacts.
- Check IRS e-Services, Tax Pro Account and CAF access for staff who need transcripts.
- Confirm state preparer registrations where required (California CTEC, New York, Oregon, Maryland).
- Track CPE hours and schedule staff training on the 2026 law changes.
Data security
- Update your Written Information Security Plan (WISP). The FTC Safeguards Rule requires one for tax preparers; IRS Publication 5708 provides a template.
- Enforce multi-factor authentication on email, portals and tax software.
- Run phishing training before January; tax pros are prime targets.
- Encrypt client files and test your backups.
- Remove system access for departed staff and seasonal workers.
Engagement and client paperwork
- Update and send engagement letters for every return, with scope, fees and deadlines.
- Refresh client organizers with the Part 2 questions.
- Set up the Form 8879 e-file signature process (e-signature with identity verification).
- Prepare Form 8867 due diligence procedures for EITC, CTC, AOTC and head of household claims.
- Agree on your extension policy (Forms 4868 and 7004) and tell clients the document cutoff date.
Software and workflow
- Install tax software updates and confirm licenses for every seat.
- Test integrations: portal, e-signature, document management and practice management.
- Roll forward client files and verify prior-year carryovers.
- Standardize review checklists for 1040, 1120-S, 1065, 1120, 1041 and 990 returns.
- Define who logs in documents, who assigns returns and how missing items are escalated.
Capacity planning
- Forecast return volume by type and complexity.
- Map staff availability, planned leave and new-client onboarding.
- Decide early whether you need seasonal or outsourced help; waiting until March is too late.
- Hold a kickoff meeting covering priorities, deadlines, review standards and client service rules.
Part 4: 2027 Tax Deadline Calendar
Missed deadlines mean penalties for clients and liability for your firm. Load these dates into your practice management system with alerts 30, 14 and 7 days out.
| Date (2027) | Deadline | Who it affects |
|---|---|---|
| Friday, January 15 | Q4 2026 estimated tax payment | Self-employed, investors, business owners |
| Monday, February 1 | W-2s and 1099-NEC to recipients and the IRS; most other 1099s to recipients | Employers and payers |
| Monday, March 15 | Form 1065 and Form 1120-S returns or extensions (Form 7004) | Partnerships, multi-member LLCs, S corporations |
| Thursday, April 15 | Form 1040 returns or extensions (Form 4868) | Individuals and sole proprietors |
| Thursday, April 15 | Form 1120 returns or extensions | Calendar-year C corporations |
| Thursday, April 15 | Form 1041 returns or extensions | Trusts and estates |
| Thursday, April 15 | Q1 2027 estimated tax payment | Estimated taxpayers |
| Thursday, April 15 | FBAR (FinCEN 114), automatic extension to October 15 | US persons with foreign accounts over $10,000 |
| Monday, May 17 | Form 990 returns or extensions | Calendar-year nonprofits |
| Wednesday, September 15 | Extended Form 1065 and 1120-S returns | Partnerships and S corporations |
| Friday, October 15 | Extended Form 1040 and 1120 returns; extended FBAR | Individuals and C corporations |
Dates are adjusted for weekends. Always confirm against the IRS tax calendar, since disaster relief can postpone deadlines for specific states or counties.
Part 5: Client Communication Timeline
Clients who hear from you early send documents early. Use this schedule.
| When | Send |
|---|---|
| November | Year-end planning note: estimated payments, retirement contributions, charitable giving under the new rules |
| Early December | Engagement letter and fee confirmation |
| First week of January | Client organizer plus the tax prep checklist from Part 1, with a portal upload link |
| Mid-January | Reminder of the document cutoff date (for example, February 15 for business returns, March 1 for individual returns) |
| Two weeks before cutoff | Personal list of each client’s missing items |
| After cutoff | Extension notice for clients whose documents are incomplete |
| After filing | Summary of what was filed, balance due or refund, and next estimated payment dates |
| May | Post-season check-in to start year-round planning |
Short on staff this tax season? Corient’s US-trained team handles return preparation, bookkeeping catch-up and review support inside your existing software, so your staff can focus on advisory work.
How Corient Supports CPA Firms During Tax Season
Many firms have the checklist but not the capacity to run it. Corient Business Solutions provides outsourced tax preparation and planning built for US CPA firms. We work inside your tax software and portal, follow your review checklists, and scale up for March and April.
Typical support includes:
- Preparing 1040, 1120-S, 1065 and 1120 returns for your review
- Bookkeeping catch-up for clients whose books are not ready
- Organizing and indexing client documents as they arrive
- Extension-season overflow work (see our guide to tax extension season outsourcing)
If you are still comparing providers, read how to choose the right CPA outsourcing partner.
Final Check: Is Your Firm Ready for Tax Season?
Before January 1, confirm every item below:
- All preparer PTINs renewed for 2027
- WISP reviewed and staff trained on security
- Engagement letters and organizers sent
- Tax software updated and integrations tested
- 2027 deadline calendar loaded with alerts
- Review checklists standardized by return type
- Capacity plan complete, with outsourced help arranged if needed
People Also Ask:
What documents do I need for tax prep?
At minimum: last year’s return, IDs and SSNs for everyone on the return, all W-2s and 1099s, bank and brokerage statements, records of deductions such as mortgage interest and donations, and proof of estimated payments. Business owners also need a year-end P&L, balance sheet and entity-specific records.
What should a business tax preparation checklist include?
Financial statements, bank reconciliations, payroll filings, asset and depreciation records, 1099s issued and received, and formation documents. S corporations add shareholder W-2s and basis worksheets; partnerships add capital accounts and the partnership agreement.
When should clients send their tax documents?
Most forms arrive by February 1, 2027. Ask business clients for documents by mid-February so you can meet the March 15 deadline, and individual clients by early March for April 15. K-1s often arrive late, so plan extensions for clients who receive them.
What changed for tax year 2026 returns?
The 1099-NEC threshold rose to $2,000, the SALT cap is $40,400, and new deductions apply for tips, overtime, seniors 65+, car loan interest and charitable gifts by non-itemizers. The standard deduction is $32,200 for married couples filing jointly.
What should a CPA firm do before tax season starts?
Renew PTINs by December 31, update the WISP, send engagement letters and organizers, update tax software, standardize review checklists and plan staffing capacity.
How long does a CPA take to prepare a tax return?
A simple individual return can take one to two hours of preparer time. Business returns and complex individual returns take several hours or days, and total turnaround depends mainly on when complete documents arrive.
Can outsourcing help a CPA firm during tax season?
Yes. An outsourced team can prepare returns for your review, catch up bookkeeping and organize documents, which reduces overtime and frees senior staff for review and advisory work.
Conclusion
A tax prep checklist works when both sides use it: clients know what to send, and your firm knows what must be ready. Send the Part 1 list in early January, build the 2026 law changes into your organizers, and complete the firm readiness items before December 31.
If your firm needs more capacity for the 2027 season, talk to Corient about outsourced tax preparation support.
