How Accountants File 1099s for Multiple Clients: A Year-End Workflow

Direct Answer

To file 1099s for multiple clients, set each client up as its own issuer, collect every client’s payee data in one consistent Excel format, run TIN matching before January, and file through a provider that e-files to IRIS under its own Transmitter Control Code. Start in November. The 1099-NEC deadline for tax year 2026 is February 1, 2027, with no automatic extension, so a January-only process leaves no room for client delays.

Key Takeaways

Treat each client as a separate issuer with its own EIN, name, and address.
Send clients one standard Excel template so every file imports the same way.
Run TIN matching in November and December, while there is still time to chase W-9s.
After January 1, 2027, IRIS is the only IRS e-file system, so confirm your provider transmits to IRIS.
Plan state filing separately: CF/SF covers participating states, but some states require a direct filing.

Why Multi-Client Filing Breaks Down in January

When you file for one business, a missing W-9 is a nuisance. When you file for 40 clients, it is 40 chances for something to be late. The problem is rarely the filing itself. It is the data: incomplete vendor lists, names that do not match TINs, contractors paid through a card processor who do not belong on a 1099-NEC at all.

The firms that get through January calmly treat 1099 season as a project that starts in the fall.

Step 1: Set Up Each Client as a Separate Issuer

Every client is the payer on its own returns. Confirm the legal name, EIN, and address for each one, and make sure they match what the IRS has on file. A typo in the issuer EIN affects every form you file for that client.

If you used 1099 Express last year, your 2025 files can be brought forward into your account. Importing them in the fall means your client and recipient lists are ready before the rush.

Step 2: Standardize Data Collection

Send every client the same Excel template and ask for the same columns: payee name, TIN, address, amount, and payment type. When client files arrive in a consistent layout, review goes faster and imports are predictable.

1099 Express offers free Excel templates for 1099-NEC and 1099-MISC. Enter data in the same column order and it imports directly. We accept Excel files only, not CSV.

Step 3: Screen Payees Before They Become Forms

Ask each client two questions about every payee:

Was this payment for services or something else? Services generally go on 1099-NEC. Rents, royalties, prizes, and attorney gross proceeds go on 1099-MISC.
How was it paid? Payments made by credit card or through a third-party network are generally reported by the payment processor on 1099-K, not by your client.

Then apply the thresholds. For payments made in 2026, the 1099-NEC threshold is $2,000, and it will be adjusted for inflation starting in 2027. Some 1099-MISC categories differ: royalties are reportable at $10, and gross proceeds paid to attorneys at $600.

Step 4: Run TIN Matching Early

Name and TIN mismatches are the biggest source of rejected returns, corrections, and IRS B-notices. Run TIN matching before you file, not after. When a mismatch comes back in November, your client has weeks to request a new W-9. In late January, they have days.

1099 Express offers interactive TIN matching at $1 per recipient (up to 25 per submission) and bulk TIN matching at $75 per file (up to 10,000 records). Both are checked against IRS records.

Step 5: Decide How Each Client’s Returns Get Filed

After January 1, 2027, the IRS will accept electronic information returns only through IRIS, including corrections and prior-year returns. Your options:

File through software that transmits to IRIS for you. 1099 Express e-files to IRIS using our own TCC, so your firm does not need one.
Hand the whole job to a service bureau. Upload the data, and the bureau e-files, prints, and mails recipient copies.

Many firms do both: they handle simple clients in-house and send high-volume clients to the service bureau.

Step 6: Do Not Forget the States

The Combined Federal/State Filing Program (CF/SF) forwards eligible returns to participating states, and 1099 Express includes it at no extra charge. Not every state participates, and some participating states still require their own filing. For 2026, Missouri was removed from the program.

Direct state filing is a separate step. You create an individual state file and process it apart from the federal submission. Check each client’s states on our State Filing page.

Step 7: Build a Correction Plan Before You Need One

Corrections happen, especially with multiple clients. A Type 1 correction can fix any field on a form, including the TIN. A Type 2 correction is only for a return filed on the wrong form: the incorrect form is zeroed out and a new original is filed on the correct one. Keep your client confirmations together so you can find the original filing quickly.

Let Our Service Bureau Carry the Volume

The 1099 Express Service Bureau handles e-filing to the IRS IRIS system and SSA, Print & Mail, and TIN matching for you. Upload by 4:30 PM CST for same-day processing and confirmation. When you order Print & Mail at the same time, e-filing is included at no extra charge. Volume pricing is available.

Start at 1099express.com, see the Service Bureau details, or talk to our team at support@1099express.com or (361) 884-1500.