82 tax deadlines that do not send a reminder
Every tax calendar you have ever seen lists filing due dates - April 15, the quarterlies, the extensions. The IRS publishes those, and so does every firm in the country.
This is the other list. The elections, the windows, the clocks. Most of them are irreversible. Most of them arrive with no form, no notice, and no letter. Each entry below tells you how long you have, what happens if you miss it and where the rule comes from.
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Disclaimer: This is general information, current as of the review date shown on each entry. This is not advice for your situation; rules change and facts matter. If one of these looks like it applies to you, talk to us or to your own advisor before acting.
Real Estate Owners
The sharpest clocks in the tax code, and the only ones with no extension procedure at all.
45
days to identify
§1031 exchange — identification period
Forty-five days from the date you transfer the relinquished property to identify replacement property in writing. Not from close of escrow on the new property — from the transfer of the old one.
1
year to file the exemption
Prop 19 — the clock nobody knows about
Everyone hears about the three-year window for the BOE-19-P claim form. Almost nobody hears about this one: the transferee must move in as their principal residence and file for the homeowners’ or disabled veterans’ exemption within one year of the transfer.
Sept 15
annual window closes
Santa Clara County assessment appeal
The regular assessment appeal window runs July 2 to September 15. Santa Clara is a September 15 county because the Assessor mails value notices to all real property owners by August 1.
No
deadline at all
Cost segregation — the myth, corrected
You do not have to do a cost segregation study in the year you buy. That widely repeated claim is simply false. What has a deadline is the mechanism for catching up on missed depreciation.
Closed
Dec 31, 2025
Residential clean energy credit — already gone
The §25D residential clean energy credit allows nothing for expenditures made after December 31, 2025. The §25C energy efficient home improvement credit ends for property placed in service after the same date.
Original
return only
Real estate professional — the grouping election
Two tests, both required, every year: more than half your personal services in real property trades where you materially participate, and more than 750 hours. Spousal hours cannot be combined for either test. The §1.469-9(g) election to treat all rentals as one activity is filed with your original return and binds all future years.
25%
and 37% — know which
Depreciation recapture — the cost-seg trade-off
Unrecaptured §1250 gain is capped at 25%. §1245 recapture is ordinary income — up to 37% federal. For real property placed in service after 1986, §1250 ordinary recapture is generally zero, because straight-line MACRS creates no excess depreciation.
$25,000
California ceiling
California does not follow the federal write-offs
Federal §179 for 2026 is $2,560,000 with a $4,090,000 phase-out threshold. California’s limit is $25,000 with a $200,000 threshold — roughly a hundredfold gap. California has also never allowed federal bonus depreciation.
180
days to close
§1031 exchange — and the trap that shortens it
You must receive the replacement property within 180 days of the transfer — or by your return due date including extensions, whichever comes first. Both clocks start on the same day.
3
years, or sooner
Prop 19 — the claim form itself
BOE-19-P is timely if filed within three years of the transfer, or before the property is transferred to a third party, whichever is earlier. There is a backstop: six months after a notice of supplemental or escape assessment is mailed.
60
days from the notice
Supplemental or escape assessment appeal
Sixty days from the date of your Supplemental Notice or Escape Enrollment Notice — measured from the mailing date printed on the notice or the postmark, whichever is later.
Jan 19
2025 — the acquisition line
Bonus depreciation — it turns on the acquisition date
100% bonus depreciation is back and permanent, but the gate is when the property was acquired, not when it was placed in service. Acquired after January 19, 2025 → 100%. Acquired before January 20, 2025 → 20% for 2026 placements, still on the old phase-down.
Closed
June 30, 2026
§179D and §45L — closed six weeks ago
§179D allows nothing for property whose construction begins after June 30, 2026. §45L allows nothing for a qualified new energy efficient home acquired after June 30, 2026.
Daily
contemporaneous log
Short-term rental — the seven-day rule, honestly
An average customer stay of seven days or less takes the activity out of the per-se passive rental rule. That is a factual measurement, not an election — nothing to file.
$2,000
not $600 anymore
1099 threshold changed for 2026 payments
For payments made in tax years beginning after 2025, the 1099-NEC and 1099-MISC reporting threshold rose from $600 to $2,000, with inflation indexing from 2027.
Restaurants
Most of these are payroll deadlines, which means they carry penalties from the first day late.
$100k
next business day
The deposit rule that changes your schedule permanently
Accumulate $100,000 or more of employment tax liability on any day and the deposit is due by the close of the next business day.
10th
of the following month
Employee tip reporting
Employees must report cash tips to the employer in a written statement by the 10th day of the following month, unless tips from that employer were under $20 for the month. Form 4070 or any equivalent record with signature, name, address, SSN, period, and total.
Jan 31
no e-file extension
W-2 and 1099-NEC — and a correction worth knowing
1099-NEC is due January 31 regardless of filing method. The March 31 e-file date applies to 1099-MISC and most other 1099s — not the NEC. Published deadline calendars get this wrong constantly. W-2 to SSA and to employees: February 1, 2027 for 2026 wages.
20
calendar days per hire
California new hire reporting — DE 34
Report every new employee within 20 calendar days of their first day of work. A rehire counts as new if they were away at least 60 consecutive days.
24th
of the month
CDTFA sales tax prepayments
If your estimated tax liability averages $17,000 or more per month, CDTFA notifies you in writing that you must prepay — on the 24th of the month following the first month of the quarter, and again on the 24th following the second.
$5.15
not $7.25
FICA tip credit — money most California operators leave behind
The §45B credit refunds the employer’s 7.65% FICA on tips above the wage floor. For food and beverage establishments that floor is frozen at $5.15/hour — the January 1, 2007 rate. The $7.25 figure applies to beauty services, not restaurants.
FLSA
§7 premium half only
"No tax on overtime" — smaller than it sounds in California
§225 allows up to $12,500 ($25,000 joint), phasing out above $150,000 or $300,000 MAGI, for 2025 through 2028. But it covers only overtime required under FLSA §7, and only the premium half — in time-and-a-half, just the 0.5x portion.
Closed
Feb 1 and Mar 30, 2026
SB 294 — two deadlines most operators have already blown
The Workplace Know Your Rights Act took effect January 1, 2026. An annual written notice covering seven subjects was due by February 1, 2026, in the language the employee understands. Employees had to be given the chance to designate an emergency contact by March 30, 2026.
2/5/10/15
percent, by days late
Failure-to-deposit penalties escalate by the day
Not more than 5 days late: 2%. More than 5 but not more than 15: 5%. More than 15: 10%. Still unpaid after notice and demand: 15%. Calendar days from the due date, and one rate applies to the whole underpayment.
80
hours, not 10 heads
Form 8027 — the most-missed filing in the industry
Required of a "large food or beverage establishment" — tipping customary and more than 10 employees on a typical business day. But the test in the instructions is an hours test: if average employee hours on a typical business day exceed 80, you must file.
TP + TT
new W-2 boxes for 2026
You are already behind on this one — and there is still time
The 2026 W-2 instructions create box 12 code TP for total cash tips reported, box 12 code TT for qualified overtime compensation, and box 14b for the Treasury Tipped Occupation Code. 2025 had transition relief. That relief is gone for 2026 wages.
$20
per wage item
DE 9 and DE 9C — the penalty that compounds
Due the 1st of the month after quarter close, delinquent after the last day of that month. Late filing: 15% of late contributions and PIT withheld. Missing or incorrect information: $20 per wage item.
Prong B
the one you cannot pass
Worker classification — why no paperwork saves a 1099 cook
Under the ABC test the worker is presumed an employee unless you prove all three: free from control, work outside the usual course of your business, and customarily engaged in an independent trade of the same nature.
$25,000
employee deduction only
"No tax on tips" — what it does not do
§224 gives the employee a deduction of up to $25,000, phased out $100 per $1,000 of MAGI over $150,000 (or $300,000 joint), for tax years 2025 through 2028. Available whether or not they itemize, but it does not reduce AGI.
$70,304
exempt salary floor
Your salaried manager may have stopped being exempt on January 1
California’s exempt salary threshold is twice the state minimum wage for full-time work. With the state minimum at $16.90 for 2026, that floor is $70,304. San José’s local minimum rose to $18.45.
Nov
2026 announcement
California FUTA credit reduction — budget for it
California is a credit reduction state. For 2025 the rate was 0.012, making FUTA effectively 1.8% instead of 0.6% on the first $7,000 per employee — about $84 more per employee. The 2026 draft Schedule A lists California again but shows the rate as "0.0XX".
Small Businesses
Elections, not filings. Almost all of them are decided long before anyone prepares a return.
2mo 15d
into the tax year
S-corp election — Form 2553
File no more than 2 months and 15 days after the tax year begins, or any time during the preceding year. For a calendar-year entity that computes to March 15.
30/40/0/30
not four equal payments
California estimated tax — the most expensive habit in the state
California does not use four equal installments. It requires 30% in April, 40% in June, nothing in September, and 30% in January. Same due dates as federal, completely different amounts.
Expired
the LLC first-year break
The $800 first-year exemption — gone for LLCs, alive for corporations
The AB 85 first-year exemption applied only to tax years beginning before January 1, 2024. It is not in effect. An LLC formed in 2026 owes $800 for 2026, due the 15th day of the 4th month after you file with the Secretary of State. But corporations still get their first-year waiver — permanently.
Aug 1
2026 — new requirement
You may not be able to see your own filing
Since August 1, 2026, the California Secretary of State requires bizfile User Access for Statement of Information filings. The option to file online is only visible to users who have established access.
Apr 15
no extension for this one
Solo 401(k) — the deadline hidden inside the deadline
A Solo 401(k) can be established by your filing due date including extensions. But SECURE 2.0 §317 lets a sole proprietor with no employees make retroactive elective deferrals only if the plan is adopted by the filing deadline without regard to extensions.
None
for U.S. entities
FinCEN beneficial ownership — where this actually stands
FinCEN issued a final rule on August 11, 2026 confirming that companies created in the United States are no longer reporting companies. Domestic entities have no BOI filing obligation, no obligation to update prior filings, and the rule directs FinCEN to delete previously submitted U.S.-person information.
12.5%
not the whole election
California PTET — a deadline that got less deadly
The pass-through entity elective tax runs through 2030 at 9.3%. The June 15 prepayment is the greater of $1,000 or 50% of the prior year’s PTET.
Nov 15
California, not October
California extension periods are not the federal ones
Extended California due dates differ: Form 100 for C corporations gets seven months to November 15, Forms 565 and 568 get seven months to October 15, Form 100S gets six to September 15.
60
month lock
Entity classification — Form 8832 and the five-year door
An election cannot take effect more than 75 days before it is filed, nor more than 12 months after. Then the lock: once you elect, you generally cannot elect again for 60 months.
$20k
once, then forever
California mandatory e-pay is a one-way door
Once you make an estimate or extension payment over $20,000, or file a return with a total tax liability over $80,000, all your future California payments must be electronic.
June 15
on gross, not profit
California LLC fee — and why it hurts low-margin businesses
On top of the $800: $900 at $250,000 of total California income, $2,500 at $500,000, $6,000 at $1,000,000, $11,790 at $5,000,000. Form 3536 estimated fee is due the 15th day of the 6th month — June 15.
6
month filing window
Statement of Information
Corporations file annually in their registration month; LLCs and nonprofits every two years. The window is six months long — your anniversary month plus the five months before it. SI-550 for stock corporations, LLC-12 for LLCs.
Oct 1
hard date
SIMPLE IRA — setup and the notice window
A SIMPLE IRA can be effective on any date from January 1 through October 1. Not extendable. The exception is a brand-new employer coming into existence after October 1, who sets one up as soon as administratively feasible. The annual employee notice must go out before the election period — generally November 2 to December 31.
2015
vs 2025 — the gap
California did not follow the 2025 federal tax bill
SB 711 moved California’s conformity date to January 1, 2025. OBBBA was enacted July 4, 2025. California picked up ten years of federal changes and then stopped one step short of the biggest business tax bill in years. The FTB says it plainly: California does not conform to OBBBA.
$220
per owner per month
Late partnership and S-corp returns scale with your owner count
Form 1065 and 1120-S are due the 15th day of the 3rd month — March 15 for calendar-year filers, extending six months to September 15. Form 1120 is the 15th day of the 4th month.
First
return you ever file
Your accounting method is chosen by accident
A new business does not elect an accounting method. It adopts one by filing its first return. There is no form, no notice, and no deadline reminder. The 2026 gross receipts threshold for the cash method is $32,000,000.
International Families & Founders
The densest concentration of silent deadlines anywhere in the code — including one that never closes, because it never starts.
Never
the clock that never starts
The unfiled form that keeps your entire return open — forever
§6501(c)(8) suspends the assessment period when a required international information return — 5471, 5472, 8938, 3520, 8865, 926, 8621 — is not filed. The clock does not begin until the form is furnished, and then three more years run.
Apr 15
auto-extends to Oct 15
FBAR — the extension nobody has to ask for
FinCEN Form 114 is due April 15, with an automatic extension to October 15 — no request, no form, nothing to file. Triggered when your foreign accounts in aggregate exceed $10,000 at any point in the year. One $4,000 account and one $7,000 account is a filing.
$25,000
even with no income
Form 5472 — the filing a dormant LLC still owes
A foreign-owned US single-member LLC has no income tax filing requirement — and must still file a pro-forma Form 1120 with Form 5472 attached, by that return's due date including extensions. Only the name, address, and two boxes on the 1120 get completed.
Mar 15
a month before you expect
Form 3520-A — due a month before Form 3520
The two foreign trust forms have different due dates and different extension forms. Form 3520-A is due the 15th day of the 3rd month — March 15 — and extends via Form 7004. Form 3520 is due April 15, or June 15 if you qualify abroad, and extends with your return.
Day 1
of the examination
Streamlined — the door closes the moment an audit opens
The Streamlined Filing Compliance Procedures are still available. Domestic filers pay a 5% miscellaneous offshore penalty; those who qualify as non-residents pay nothing. Three years of returns, six years of FBARs, and a non-willfulness certification.
8833
the form that can detonate
The treaty claim that can end your residency
A green card holder who claims to be a resident of another country under a treaty tie-breaker, does not waive the treaty benefits, and notifies the IRS, ceases to be a lawful permanent resident for tax purposes. The notification is Form 8833.
5 years
of compliance, certified
Form 8854 — how modest people become covered expatriates
Form 8854 must be attached to your final return and a separate copy mailed to the IRS in Austin. Both steps. Filing only the return copy is the common failure.
Next year
before you can elect
First-year choice — an election you cannot make on time
The first-year choice under §7701(b)(4) lets someone who arrives mid-year be treated as a resident from their arrival date. But the regulation is explicit: you may not make the election until you have satisfied the substantial presence test for the year following the election year.
183
days, weighted
Closer connection — the exception with a hard ceiling
Form 8840 lets someone who meets the substantial presence test still be taxed as a nonresident, if they had a tax home abroad and a closer connection to that country. It is filed by the Form 1040-NR due date including extensions.
Dec 31
of the third unused year
Your ITIN expires quietly, right before filing season
An ITIN not used on a federal return for three consecutive years expires on December 31 of that third year. Renewal is Form W-7 marked as a renewal, with original or certified identity documents.
18
months, not twelve
A gift from a covered expatriate taxes the person receiving it
§2801 imposes a 40% tax on covered gifts and bequests received from a covered expatriate — and it falls on the US recipient, not on the person who left. Reported on Form 708, with a $19,000 annual exclusion for 2025 and 2026.
Year 1
or the door shuts
PFIC — the election you must make before you know you need it
A QEF election under §1295 must generally be made by the due date, including extensions, of the return for the first year of the holding period. Make it then and the fund is "pedigreed" — clean annual inclusions. Make it later and it is "unpedigreed," and §1291 keeps applying until you purge it.
$50k
and it is not the FBAR
Form 8938 — a second form for the same accounts
Thresholds for filers living in the US: $50,000 at year end or $75,000 at any time if unmarried; $100,000 / $150,000 filing jointly. Living abroad: $200,000 / $300,000 unmarried, $400,000 / $600,000 joint. It attaches to your return.
$10,000
per form, per year
Form 5471 — owning a piece of a foreign company
Required of US persons in five categories of ownership, officership, or control in a foreign corporation. It attaches to your return and is due with it, including extensions.
$100,000
a gift is not income
The foreign gift nobody thinks is reportable
Receiving more than $100,000 from a nonresident alien individual or foreign estate triggers Form 3520 Part IV. From foreign corporations or partnerships the threshold is far lower and indexed: $20,116 for 2025 gifts, $20,573 for 2026. Related-party gifts aggregate.
8 of 15
years, counted loosely
The green card clock nobody is watching
Hold a green card in at least 8 taxable years out of the last 15 and you become a "long-term resident" — which means that if you ever hand the card back, you are tested for the exit tax. The statute counts taxable years in which you were a lawful permanent resident at any time, not eight full years.
$2M
unindexed since 2004
The exit tax threshold that Silicon Valley crossed years ago
You are a covered expatriate if any one of three tests is met: average annual net income tax over the prior five years above $211,000 for 2026; net worth of $2,000,000 or more; or failure to certify five years of tax compliance. All property is then treated as sold the day before you leave, with the first $910,000 of gain excluded for 2026.
Once
in a lifetime, truly
The election with your nonresident spouse you only get once
§6013(g) lets you treat a nonresident spouse as a US resident so you can file jointly. It applies to worldwide income, for that year and all later years, until terminated.
Any part
of a year burns a year
Student and scholar days — the counting rule that surprises everyone
F, J, M and Q students are exempt individuals for five calendar years; J and Q teachers and trainees for two of the previous six. Form 8843 is filed to claim it — required even with no income at all.
20
days after closing
FIRPTA — the buyer becomes personally liable
When a foreign person sells US real property, the buyer must withhold 15% of the amount realized — the gross price, not the gain — and file Form 8288 with 8288-A within 20 days of the transfer. Reduced to 10% for a residence between $300,000 and $1,000,000; none at or below $300,000 where the buyer will reside there.
3
calendar years, then dead
Form W-8BEN expires by the calendar, not by notice
A W-8BEN is valid from the date signed through the last day of the third succeeding calendar year. Signed September 30, 2026, it dies December 31, 2029. Certain forms bearing a US TIN remain valid indefinitely.
10
years, not three
Foreign tax credit — the one window that is longer than you think
Refund claims attributable to foreign taxes get ten years from the due date of the return for the year the foreign taxes were paid or accrued, rather than the usual three.
Equity Compensation
Thirty-day windows, December 31 boundaries, and tender offers measured in weeks.
30
days from transfer
§83(b) — the least forgiving deadline in the tax code
Thirty calendar days from the date the property is transferred — not granted. For a founder buying restricted stock that is the purchase date; for an early-exercised option, the exercise date. The option grant date is irrelevant.
42%
effective marginal AMT
The 2026 AMT change almost nobody reported
2026 exemptions: $140,200 joint, $90,100 single. The headline exemption went up, which is why this got missed. What changed underneath: the joint phase-out now begins at $1,000,000, and the phase-out rate doubled from 25% to 50%.
Never
for secondary buyers
Bought in a tender or secondary? You never had QSBS
§1202(c)(1) requires that the stock be acquired by the taxpayer at its original issue, directly or through an underwriter. That requirement survived the 2025 changes untouched.
60
days from the sale
§1045 QSBS rollover
Sixty days from the sale date to reinvest in replacement qualified small business stock. Requires that you held the original stock more than six months — not five years — that you are not a corporation, and that you affirmatively elect. It is not automatic.
One
taxable year, entire balance
Net unrealized appreciation — destroyed by a routine rollover
A lump-sum distribution that includes employer securities excludes the net unrealized appreciation from ordinary income — you are taxed on the plan’s cost basis now, capital gain on the appreciation later. It requires the balance to your credit distributed within one taxable year, on one of exactly four events: death, age 59½, separation from service, or disability.
1.3%
uncapped
California SDI on equity income — the surtax nobody budgets for
The 2026 SDI rate is 1.3% and there has been no taxable wage limit since January 1, 2024. Equity that is W-2 wages — NQSO exercise spread, RSU vesting, the ESPP discount, and the compensation element of an ISO disqualifying disposition — is fully subject to it.
20
business days
Tender offers — your actual decision window
A tender offer must stay open at least 20 business days from first dissemination, and at least 10 business days after notice of any change to the percentage sought, the consideration, or the dealer’s fee.
Dec 31
the AMT year boundary
Same-year unwind — the strategy that dies at midnight
The Form 6251 instructions say it directly: if you exercise an ISO and dispose of that stock in the same year, the regular tax and AMT treatment are the same and no adjustment is required.
July 4
2025 — the QSBS cliff
One date, two completely different QSBS regimes
Stock acquired on or before July 4, 2025 follows the old rules: five years for 100%, $10,000,000 per-issuer cap, $50,000,000 gross asset ceiling. Stock acquired on July 5, 2025 or later follows the new tiers: 3 years for 50%, 4 for 75%, 5 for 100%, a $15,000,000 cap, and a $75,000,000 asset ceiling, both indexed after 2026.
2 + 1
years, both required
ISO holding periods — and the year the income lands
To keep ISO treatment: no disposition within two years from grant and no disposition within one year from transfer of the share. Both, not either. The later one controls.
Jan 31
employer obligation
Forms 3921 and 3922 — the company files these, not you
Every corporation that transfers stock on an ISO exercise files Form 3921, one per exercise. Every corporation recording a first transfer of legal title of ESPP stock files Form 3922. Statement to the employee by January 31; to the IRS by February 28 on paper, March 31 electronically.
0%
California QSBS benefit
California taxes the gain you thought was excluded
The FTB says it in one sentence: California does not conform to the qualified small business stock deferral and gain exclusion under IRC Sections 1045 and 1202. Enter the entire gain realized.
7.0%
California AMT
California runs its own AMT — and ignored the 2025 changes
California conforms to IRC §§55–59 as of January 1, 2015. So it applies its own AMT to ISO exercises at a 7.0% rate, on its own exemption and phase-out schedule, and it does not pick up the OBBBA changes — not the $1,000,000 threshold, not the 50% phase-out rate.