1099 Season Planning Calendar: What AP Teams Should Be Doing Every Month of the Year

Most 1099 filing problems aren't January problems. They're August problems that nobody noticed. A vendor with a stale TIN, a name change that never got updated, a W-9 that was never collected for a contractor who crossed the threshold in October — these are all fixable in August. In January they're emergencies. This calendar gives you the specific actions, by month, to stay ahead of the problems before they become deadlines.

Why Filing Season Problems Start in the Summer

The January 31 deadline for Form 1099-NEC and the March 31 e-file deadline for most other 1099s feel far away in July. But the work that determines whether you sail through filing season or scramble through it happens in the second half of the year — specifically:

Whether your vendor TINs were validated before payments were made
Whether W-9s were collected from every vendor who will cross the reporting threshold
Whether name changes, EIN updates, and ownership changes were captured
Whether you have time to resolve mismatches through vendor outreach rather than backup withholding

By the time November arrives, most of those windows have closed. The vendors who won't respond to a W-9 request in November definitely weren't going to respond in August either — but in August you had time to start backup withholding before any significant payments went out. In November you're just hoping they respond.

What's Changed for 2026 Filings

Before the calendar, two threshold changes from the One Big Beautiful Bill Act (OBBBA, signed July 2025) that affect your 2026 planning:

1099-NEC and 1099-MISC threshold rises to $2,000 for 2026 payments. The $600 threshold still applies to 2025 payments (forms due in early 2026). Starting with payments made on or after January 1, 2026, reporting is only required when aggregate payments reach $2,000. This reduces your filing population for 2026 returns, but the transition itself creates risk — vendors paid between $600 and $1,999 in 2025 still need 1099s; the new threshold only applies to 2026 payments.

Backup withholding threshold also rises to $2,000 for 2026. Withholding obligations align with the new reporting threshold.

The practical effect: your 2025 filings (due early 2026) use the old rules. Your 2026 filings (due early 2027) use the new rules. Plan vendor master and threshold tracking accordingly for both cycles.

The Month-by-Month Planning Calendar

January - February: File and Debrief

Filing deadlines:

January 31: 1099-NEC due to recipients and IRS (both paper and e-file)
February 28: Most other 1099s due to IRS on paper
March 31: Most other 1099s due to IRS electronically

During and immediately after filing season:

Complete all 1099 filings on time. Late filing penalties start at $60 per return and climb to $330-$340 if not corrected by August 1.
File corrected 1099s promptly for any mismatches identified late. Every day you wait moves you closer to the next penalty tier.
Conduct a post-filing debrief: How many mismatches did TIN matching surface? How many W-9s were missing at year-end? How many vendors required manual outreach in December? These numbers tell you exactly where your process broke down.
Document the debrief findings. The improvements you make in February determine how Q4 goes next year.

IRS lockout risk: If you're using IRS e-Services for TIN matching and ran into a 96-hour lockout during the January crunch, document it. This is the right time to evaluate whether a third-party TIN matching service makes more sense than direct IRS submission for next year.

March - April: Watch for CP2100 Notices

CP2100 notices for the prior year's filings typically arrive in waves — one in the spring and one in the fall. The spring wave covers returns filed in January.

Actions:

Watch for CP2100 notices arriving from the IRS. The clock starts on the notice date, not when you open it.
When a CP2100 arrives, process it immediately. First B-Notices must go out within 15 business days.
Review your B-Notice tracking log from the prior year. Any Second B-Notice vendors (second appearance within three years) require IRS-certified TIN documentation, not just a self-certified W-9.
Begin backup withholding for any vendors who haven't responded to prior B-Notices.

For corrected filings: Any corrections filed before August 1 are at the lower $130 per-return penalty tier. After August 1 the rate rises to $330-$340. Keep this deadline in mind for any outstanding corrections from January filing.

May - June: W-9 Collection Sweep

This is the best time of year for a proactive W-9 collection campaign. Vendors are not in the middle of year-end close, your AP team isn't underwater, and you have months before filing season.

Actions:

Run your full vendor master through IRS TIN matching. Identify every Code 2 (TIN not issued) and Code 3 (name/TIN mismatch) result.
For each mismatch, determine whether it's a data entry error you can fix internally or whether a corrected W-9 is needed.
Launch a W-9 collection campaign for: vendors with TIN mismatches, vendors who have never provided a W-9, and vendors who provided a W-9 more than three years ago.
Update entity types for any vendors who returned Code 6 (matched as SSN) or Code 7 (matched as EIN) — this affects which 1099 form applies and whether the corporate exemption applies.
Validate all corrected W-9s through TIN matching before updating vendor master records.

Threshold monitoring for 2025: Pull a YTD payment report by vendor. Identify vendors approaching the $600 threshold (for 2025 payments) who don't have a W-9 on file. Collect W-9s now, before those vendors cross the threshold.

Threshold monitoring for 2026 transition: If you're planning ahead, identify which vendors in your current $600-$1,999 band will fall below the new $2,000 threshold for 2026 payments. Your filing population will shrink, but make sure your tracking system is set up to handle both thresholds cleanly across the transition year.

July - August: Vendor Master Cleanup

This is the window the previous months were building toward. You have validated TINs from your May-June matching run, responses from your W-9 campaign, and enough time before year-end to resolve anything that's still outstanding.

Actions:

Process all corrected W-9s received from your spring campaign. Validate each one through TIN matching before updating records.
For non-respondents from your W-9 campaign: make a second outreach attempt, then decide whether to begin backup withholding on future payments.
Run EIN lookup on any vendors where TIN matching couldn't resolve the mismatch and the vendor hasn't responded. EIN discovery by company name can often surface the correct EIN without requiring vendor cooperation.
Update your vendor master: correct TINs, correct entity types, correct legal names.
File any outstanding corrected 1099s before August 1. This is the last day to file corrections at the $130 per-return tier. After August 1, the rate rises to $330-$340.
Conduct a sanctions screening refresh on your full vendor list if you haven't done one since onboarding.

August 1 is the most important mid-year deadline. Any 1099 correction filed after this date is at the highest standard penalty tier. If you have outstanding corrections sitting in your queue, file them now.

September - October: Fall CP2100 Wave and Threshold Review

The fall CP2100 wave arrives for returns filed the prior March. This is also when you start getting a clear picture of which vendors will cross the reporting threshold by year-end.

Actions:

Process any fall CP2100 notices with the same urgency as the spring wave. 15-business-day deadline for First B-Notices.
Pull a YTD payment report. Identify vendors likely to cross the $600 threshold (for 2025 payments) by December 31 who still don't have a valid W-9 on file.
This is your last comfortable window for vendor outreach. A W-9 request in October is much easier to manage than one in December.
For vendors who received a First B-Notice in the spring and haven't responded: confirm backup withholding is active and begin tracking withheld amounts for Form 945 reconciliation.
Review your e-file setup. If your organization files 10 or more information returns, e-filing is mandatory. Confirm your FIRE system access or IRIS access is current.

November: Final Preparation

November is when the filing season pressure starts to build. The goal is to enter November with no outstanding W-9 gaps and no unresolved TIN mismatches — so that November is about finalizing numbers, not chasing vendors.

Actions:

Run a final TIN matching pass on any vendors added or updated since your summer cleanup.
Confirm W-9 status for every vendor who will cross the reporting threshold by year-end.
Begin backup withholding immediately for any vendor crossing the threshold without a valid TIN on file — don't wait until year-end to discover the gap.
Confirm your 1099 preparation software or process is set up for the correct tax year thresholds. 2025 filings use $600; 2026 filings use $2,000.
Run a final sanctions screening pass before year-end payments go out.
If you received a 972CG penalty notice this year, confirm your response was submitted within 45 days and document the outcome.

IRS e-Services: If you're planning to use IRS TIN matching directly through e-Services in January, verify your account access now. Don't discover a login issue or expired registration on January 28.

December: Lock Down and Prepare to File

Finalize your 1099 vendor list. Confirm payment totals, TIN/name combinations, and entity types.
Confirm backup withholding amounts for all non-respondent vendors. These need to be reconciled on Form 945 by January 31.
Run a final TIN matching pass on your complete 1099 population. Any Code 3 results at this stage should be escalated immediately for resolution before filing.
If you use TIN Comply for bulk processing: upload your final vendor file in late December to get results back with time to act before the January 31 deadline.
Brief your team on the filing calendar and who owns each step.

The Cost of Waiting vs. Acting Early

Action	Done in July-August	Done in December-January
TIN mismatch discovered	Fix the record, re-validate, file correctly	Emergency vendor outreach, possible backup withholding, possible penalty
Missing W-9 discovered	Relaxed outreach campaign, time to escalate	Frantic emails, likely deadline miss
Vendor mismatch unresolved	Begin backup withholding on future payments	Retroactive withholding calculation headache
Corrected 1099 filed	$60-$130 per return	$330-$340 per return (after August 1)
IRS e-Services lockout	96 hours to wait out, no deadline pressure	96-hour lockout may span the filing deadline

The math consistently favors early action. The same number of problems costs substantially less to resolve in August than in January.

How TIN Comply Supports Year-Round Filing Preparation

IRS TIN Matching - run your full vendor list any time of year; results typically within the hour with no IRS lockout risk
W-9 Collection - automated vendor outreach for proactive W-9 campaigns in May-June and follow-up in October
EIN Lookup - resolve stubborn Code 3 mismatches without vendor cooperation
Bulk File Processing - validate your complete vendor master with TIN matching, EIN lookup, and sanctions screening in a single submission, no 100,000-record limit
CP2100 & B-Notice Handling - managed service for the full B-Notice response workflow when CP2100 notices arrive

Start a free trial or request a demo.

Key Dates at a Glance

Date	Action
January 31	1099-NEC due to recipients and IRS
February 28	Most other 1099s due on paper
March 31	Most other 1099s due electronically
Spring (varies)	First CP2100 wave arrives
May - June	TIN matching run and W-9 campaign
August 1	Last day to file corrections at $130/return tier
September - October	Fall CP2100 wave; threshold review
November	Final TIN matching pass; confirm W-9 coverage
December	Lock down vendor list; run final bulk validation

This article is for informational purposes only and does not constitute legal or tax advice. Consult a qualified professional for guidance specific to your organization.