California S Corporation Taxation and California PTET
Why California needs its own page
The federal version of an S corporation is clean: file Form 1120-S, issue K-1s, run payroll, track basis, and you’re mostly done. California adds three things on top — an entity-level 1.5% tax on California-source income, an $800 minimum franchise tax that almost always applies, and an optional pass-through entity elective tax with timing rules that bite hard if you miss them. None of that lives in the federal guide, and it has to be priced into the modeled savings before the structure goes live.
This page is the California sub-page in our four-state S-corp cluster. It pairs with the pillar guide and with the New York State and New York City sub-pages. If your operating footprint is actually in Los Angeles County, also see our piece on Los Angeles S corp tax planning, which covers the city business tax and county overlays this page doesn’t.
California’s 1.5% S corporation tax
California recognizes the federal S election but still taxes the entity itself. The Franchise Tax Board’s S corporations page states that every S corporation with California-source income is subject to a 1.5% tax, and the same rate is repeated on the FTB’s business tax rates page. That’s not a fee. It’s a real tax on net income, paid at the entity level, before anything passes through to shareholders.
The number sounds small. It isn’t. On a California S corp with $800,000 of California-source income, the 1.5% tax is $12,000 — every year, on top of whatever the shareholders owe at the personal level on the same income. That’s the line federal-only modeling almost always misses. If you’re moving from a sole proprietorship to an S corp specifically to save self-employment tax, the California 1.5% layer eats into the savings, and in low-margin or low-net-income years it can erase them entirely. We run the math both ways before we’ll sign off on a California S election.
The $800 minimum franchise tax and the first-year waiver
Every California S corporation pays at least the minimum franchise tax of $800 per year. The FTB’s S corporations page is explicit that the minimum is generally due even when the corporation is inactive, has no income, or has lost money — as long as the entity exists in California, the $800 is owed.
The carve-out is for newly formed or newly qualified S corporations filing an initial return for their first taxable year, which receive a first-year waiver of the minimum tax. Read that carefully: the waiver is on the $800 minimum, not on the 1.5% tax on California-source income. A first-year California S corp with real California income still owes 1.5% of that income — it just doesn’t owe the $800 floor on top. The 1.5% S corporation tax kicks in at $1.50 of tax per $100 of net income, so an entity with very small income still ends up owing the $800 minimum after year one anyway.
One more wrinkle: the franchise tax is paid in arrears for the year being filed but in advance for the next year, through the estimated-tax mechanics. New owners are sometimes surprised to learn they owe the $800 for year two before year one’s tax is even calculated. That’s California’s structure, not a billing error.
Form 100S, California’s S corporation return
California S corporations file Form 100S. The 2025 Form 100S booklet states that all federal S corporations subject to California law must file Form 100S and pay the greater of the minimum franchise tax or the applicable 1.5% S corporation tax on net income. The “greater of” language is the part that matters: the corporation always owes the $800 floor, and once 1.5% of net income exceeds $800, the higher number is what’s due.
Form 100S is structurally similar to the federal Form 1120-S but it’s not a copy. It uses California’s apportionment and allocation rules, has its own schedules for California-specific adjustments (depreciation, charitable contributions, NOLs that don’t conform to federal), and produces a California Schedule K-1 that flows to the shareholder’s California personal return. If your federal preparer is treating Form 100S as “federal with the cover page swapped,” that’s the failure mode we’re called in to fix — usually after a notice has already arrived. The booklet is the real source of truth, and the apportionment schedules in particular are where the work actually is.
Form 100S is generally due by the 15th day of the third month after year-end (March 15 for calendar-year filers), with a six-month automatic extension that has to be paired with a paid extension if there’s a balance due. California does not give you a free extension on payment — interest and underpayment penalties run from the original due date.
California PTET, what it is and how it works
The California Pass-Through Entity Elective Tax (commonly called California PTET, sometimes the AB 150 PTET) is California’s version of the SALT-cap workaround that most high-tax states adopted after 2017. The mechanics, in short: a qualifying S corporation or partnership pays an elective entity-level tax of 9.3% on each consenting owner’s share of qualified net income. The entity deducts the payment as a state tax on its federal return, which sidesteps the $10,000 individual SALT cap. The owner then claims a California credit equal to the PTET paid on their behalf, which offsets their California personal tax bill. The official source is the FTB’s California PTE elective tax page.
The election is annual, made on the entity’s timely-filed return, and only consenting owners are included in the calculation. Each owner has to opt in for their share to count — there’s no automatic enrollment. That sounds like flexibility, and on paper it is, but in practice it’s a coordination problem: you can’t pay the entity-level tax for an owner who hasn’t consented, and you can’t unwind a payment that was made for an owner who declines after the fact.
For most California S corps with profitable owners and high California personal tax brackets, the PTET is a real saver. The federal deduction at the entity level is worth roughly 37 cents on the dollar at the top federal bracket, while the owner’s California credit makes them whole on the state side. On a $500,000 PTET payment, the federal deduction alone is worth around $185,000 — that’s not a rounding error, and that’s why the timing rules exist and why the FTB writes about them so prominently.
The two California PTET deadlines that trip people up
The California PTET has a two-payment, two-deadline structure that catches more owners than any other California rule we deal with. The first payment is due June 15 of the taxable year. The second (the balance) is due by the original due date of the return, March 15 of the following year. The election itself is made on the timely-filed return.
The June 15 prepayment is the gate. To preserve the right to elect PTET for the year, the entity must pay by June 15 the greater of $1,000 or 50% of the prior year’s PTET liability. Miss June 15 — pay zero, pay late, or pay less than required — and the FTB’s longstanding rule was that the election was barred entirely for that year. The FTB PTE help page walks through the prepayment requirement and the consequence of missing it.
There’s a wrinkle for taxable years beginning on or after January 1, 2026 and before January 1, 2031. Per the same FTB help page, if the required June 15 payment is not made by June 15 or is less than required during that window, the election may still be valid — but the owners’ PTE credit is reduced by 12.5% of their pro rata share of the unpaid amount that was due June 15. That’s a softening, not a free pass. You’re still losing 12.5% of credit on the unpaid portion. For a $500,000 PTET liability with a $250,000 prepayment requirement, missing the prepayment costs roughly $31,250 of credit at the owner level. We’d rather see the prepayment go out on time.
Practical sequence: in May, look at the prior year’s PTET liability and the current year’s projection. Calendar June 15 as a hard deadline. Wire the greater of $1,000 or 50% of last year’s liability. File the second payment with the return at March 15. Make the actual election on the timely-filed Form 100S. That’s the operating rhythm. Anything less and you’re betting on a relief provision that may or may not save you.
State deadlines that actually matter for California S corps
Pulling the deadlines into one list:
- March 15 — Form 100S is due (calendar-year filers). Final PTET balance due. PTET election made on the timely-filed return. Federal Form 1120-S also due, so this is the real S-corp filing day.
- April 15 — Q1 California estimated tax payment for the corporation, if estimates are required. Also Q1 personal estimates for shareholders.
- June 15 — California PTET prepayment due (greater of $1,000 or 50% of prior-year PTET). Q2 corporate estimates also due. This is the date that breaks PTET planning when missed.
- September 15 — Q3 corporate estimates. Extended deadline for Form 100S if a six-month extension was filed.
- December 15 — Q4 corporate estimates.
California estimated tax for the entity itself works on a pay-as-you-go basis at 30%, 40%, 0%, and 30% of the estimated annual tax — an unusual schedule that catches preparers used to the federal 25%/25%/25%/25% rhythm. Underpayment penalties run on Form 5806 if the corporation doesn’t keep pace. None of this is in the federal cluster, which is why it lives here.
What this means in practice
Here’s an opinionated take. A California S corporation makes sense when three things are true at once: California-source net income is high enough that the federal self-employment-tax savings clearly exceed the 1.5% California entity tax plus the $800 minimum, the owner has California personal tax exposure large enough to make the PTET federal deduction meaningful, and someone in the engagement is going to actually run payroll and hit the June 15 PTET prepayment. If any one of those is missing, the structure usually doesn’t pencil.
It doesn’t make sense in some predictable cases. If California net income is small (say, under $50,000), the 1.5% tax plus the $800 minimum often wipe out the FICA savings the federal structure was supposed to deliver. If the owner is a part-year resident or California-source income is small relative to total business income, the apportionment work can cost more in preparation fees than the structure saves. If nobody is going to manage the PTET prepayment calendar, the owner is leaving the largest single piece of California S-corp tax savings on the table — and at that point, you’d often be better off as an LLC taxed as a partnership or even a sole proprietorship, both of which avoid the 1.5% entity tax entirely.
The other live question is California’s reasonable-compensation exposure. The FTB tends to follow the IRS lead here, which means the federal wage analysis governs, but California’s audit selectors are independent, and a wage that survives the IRS doesn’t automatically survive the FTB. We build the comp memo with both audiences in mind. Our entity formation and structuring service is where we do the modeling before the election goes in, and our corporate returns work is where Form 100S, the PTET calculation, and the apportionment schedules actually get prepared.
Common California-specific mistakes
- Modeling federal S-corp savings without including the 1.5% California entity tax or the $800 minimum.
- Assuming the first-year waiver also waives the 1.5% tax. It doesn’t — the waiver is on the $800 minimum only.
- Filing Form 100S as if it were a translated Form 1120-S and missing California’s separate apportionment, depreciation, and NOL rules.
- Skipping the June 15 PTET prepayment because the actual election doesn’t get made until March of the following year. The election is made on the return; the right to elect was preserved by June 15.
- Calculating the June 15 prepayment off current-year projections instead of the statutory floor (greater of $1,000 or 50% of prior year’s PTET).
- Forgetting that the PTET only covers consenting owners — running the calculation as if all owners are in, then discovering one declined.
- Treating the 30/40/0/30 California estimated-tax schedule as the federal 25/25/25/25 split. The penalty math is different.
- Letting a California-source income computation drift across years because of inconsistent apportionment factors.
If you want background on how the federal mechanics map to the personal return, see how we handle individual tax returns. The federal context for everything on this page lives in our federal S corporation guide, and the broader IRS overview is at the IRS S corporations page.
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Frequently Asked Questions
How does California S corporation tax differ from the federal pass-through result?
The short answer is that California S corporation tax is not a pure pass-through. The federal version is. Once a corporation files Form 2553 and is accepted into Subchapter S, federal taxable income flows through to shareholders on K-1s, the entity itself owes no federal income tax (with narrow built-in-gains and excess-net-passive exceptions), and the federal answer is essentially clean. California S corporation tax does not work that way. The state recognizes the federal S election, but it imposes its own entity-level taxes that the federal regime does not — a 1.5% tax on California-source net income, a $800 minimum franchise tax, and an optional pass-through entity elective tax. Each one is its own check, paid by the corporation, before anything passes through to shareholders for California personal tax purposes.
That gap is the single biggest reason California S corporation tax planning differs from federal planning. A federal-only model says: the S corporation saves self-employment tax on the distribution portion of owner profit. A California-aware model has to net that savings against 1.5% of California-source income, plus $800, plus the prep cost of Form 100S and California Schedule K-1s. The headline FICA savings are real, but in California they’re partially offset, and in low-income years they can be entirely offset. The California S corporation tax math has to be run on the actual numbers, not the federal slide.
The second piece of the difference: deadlines and elections. Federal S corporations file Form 1120-S by March 15 and that’s it for federal entity tax. California S corporation tax requires Form 100S by the same date, plus quarterly estimated tax payments on a 30/40/0/30 schedule (not the federal 25/25/25/25), plus the California PTET June 15 prepayment if the entity wants to preserve the right to elect that year. Missing any of those creates penalties or lost elections that don’t have federal analogs. The 2025 Form 100S booklet is the official source for the California return, and the FTB S corporations page covers the entity-tax structure.
Third piece: shareholder mechanics. A federal K-1 produces an amount the shareholder reports on Schedule E of the 1040. California S corporation tax produces a separate California K-1 (Schedule K-1, Form 100S) that flows to the shareholder’s California Form 540 with potentially different numbers — California depreciation differences, California NOL conformity issues, California credits, and so on. Nonresident shareholders have additional California-source income reporting through Schedule R apportionment. The federal-California reconciliation is real prep work, and it’s one of the places we see other preparers cut corners. The IRS overview is at IRS S corporations; the California version sits beside it, not on top of it.
Fourth piece: the California PTET layer. There is no federal equivalent. The federal S election is the federal answer. California PTET is an additional, optional regime on top, with its own election, its own payment schedule, its own credit mechanics at the shareholder level, and its own paperwork. A federal-only practitioner is going to miss it, and the cost of missing it on a profitable California S corp is large enough to fund the entire engagement several times over. Form 100S, California PTET, the 1.5% entity tax, and the $800 minimum are the four California layers that aren’t in the federal cluster — and they’re why this page exists separately from the federal guide.
What is the California S corporation 1.5% tax actually levied on?
The California S corporation 1.5% tax is levied on the corporation’s California net income — not on gross receipts, and not on shareholder-level distributions. The base is the entity’s net income for the year, computed under California rules (which conform to federal in most areas but not all), then apportioned to California using the standard single-sales-factor formula for most businesses. The result of that apportionment is “California-source net income,” and 1.5% of that figure is the entity-level tax, subject to the $800 floor.
The mechanics matter because the California S corporation 1.5% tax is sometimes confused with a gross-receipts tax or a franchise fee. It’s neither. It’s a net-income tax with a low rate, and the rate’s smallness is exactly what makes the floor (the $800 minimum) so common — for most small California S corps, 1.5% of net income is actually less than $800, so the corporation defaults to paying the minimum. The rate only becomes the binding number when net income clears about $53,333, which is where 1.5% of net income equals $800.
Apportionment is where the California S corporation 1.5% tax gets technical. A California S corporation with operations in multiple states allocates business income to California using a single-sales-factor formula based on California-destination sales as a share of total sales. That’s a simplification of decades of California apportionment evolution, but it’s the current rule for most service and product businesses. The result is that two S corps with identical net income can have very different California-source income, and therefore very different 1.5% tax bills, depending on where their customers actually are. The 2025 Form 100S booklet covers the apportionment schedules and the conformity differences.
The California S corporation 1.5% tax interacts with the PTET. PTET payments made by the entity during the year are a state and local tax expense, deductible at the federal level, but they don’t directly reduce the 1.5% base — the 1.5% tax and the PTET are two separate layers on the same income, and the corporation owes both. What PTET does deliver is the federal SALT-cap workaround: by paying entity-level tax that the federal government recognizes as the corporation’s deduction (not the shareholder’s), the income that flows through to shareholders is already reduced for federal purposes. That’s the federal benefit. The 1.5% piece is a separate California cost that exists whether or not PTET is elected.
Specifically excluded from the California S corporation 1.5% tax base: most QSub income (which flows up to the parent), certain insurance company income (which has its own regime), and income that’s properly allocated to other states under apportionment. The 1.5% rate is on California-source business income only — not foreign-sourced income, not other-state-sourced income, not shareholder-level investment income. The base is narrower than a quick reading of the FTB pages might suggest, and getting the apportionment right is often where the actual planning value sits. The FTB business tax rates page confirms the 1.5% rate, but the base is in the Form 100S booklet, and the apportionment rules can shift the base by 20% or more depending on customer geography.
How does California PTET work and when does an S-corp benefit from electing it?
California PTET is the state’s optional pass-through entity elective tax, available to S corporations and certain partnerships. The mechanics: the entity elects on its timely-filed return to pay an entity-level tax of 9.3% on each consenting owner’s share of qualified net income. That payment is a state tax expense the entity deducts on its federal return. The owner then claims a nonrefundable California credit equal to the PTET paid on their behalf, which offsets their California personal income tax. The official rule set lives on the FTB’s California PTE elective tax page, with the timing and prepayment rules at the FTB PTE help page.
The reason California PTET exists is the federal SALT cap. The 2017 federal Tax Cuts and Jobs Act limited the individual itemized deduction for state and local taxes to $10,000. Owners of pass-through entities in high-tax states like California were the most affected — their California personal income tax was deductible federally only up to $10,000, when the actual liability was often much larger. California PTET sidesteps the cap by making the state tax payment at the entity level, where it’s deductible without the $10,000 limit, and then giving the owner a credit so they’re not double-paying California tax.
An S corp benefits from California PTET when several conditions line up. The owners must have substantial California personal tax exposure — generally meaning California-source income that pushes them into high California marginal brackets (the 9.3% PTET rate is calibrated to roughly match the California marginal bracket for taxable income over $61,214 for single filers and similar levels for joint filers). The owners must be in high enough federal brackets that the federal deduction at the entity level is worth meaningfully more than the lost itemized deduction at the personal level. The owners must consent to inclusion — a single non-consenting owner doesn’t kill the election but does shrink the benefit. And the entity must have the operational discipline to hit the June 15 prepayment, the March 15 election filing, and the cash flow to pay the tax.
An S corp does not benefit from California PTET when the owners have low California exposure (PTET payments don’t get refunded if the credit exceeds the personal liability — excess credit carries forward up to five years), when the owners are not California residents and have minimal California-source income, when the federal AMT or other federal-side limitations would reduce the value of the entity-level deduction, or when the cash flow to make the entity-level payment isn’t there. We’ve seen owners elect PTET because everyone else was electing it, only to discover their personal California tax was small enough that the credit sat unused for years. California PTET is not free money. It’s a federal deduction in exchange for an entity-level prepayment, and the math has to clear at both levels.
The mechanical rhythm for a California S corp electing PTET: project current-year qualified net income in May, calculate the prepayment due by June 15 (greater of $1,000 or 50% of prior-year PTET), wire it on time, project the balance in February, pay the balance with Form 100S by March 15, make the election on Form 100S, issue Schedule K-1s reflecting the credit, and have the shareholders claim the credit on their California Form 540s. Skip any step and the benefit shrinks or disappears. We coordinate this for clients as part of the corporate returns engagement; it doesn’t get bolted on at extension time.
What does Form 100S report and how is it different from the federal Form 1120-S?
Form 100S is California’s S corporation income tax return. It reports the corporation’s California-source income, applies California’s tax computation (the greater of 1.5% of net income or the $800 minimum franchise tax), shows any PTET election and payment, computes California-specific credits, and produces a California Schedule K-1 for each shareholder. The full instructions are in the 2025 Form 100S booklet. Structurally, it’s the California analog of the federal Form 1120-S, but the two returns are not interchangeable.
The first major difference is the entity-tax computation. Form 1120-S generally produces no federal tax at the entity level — the federal answer is pure pass-through with narrow exceptions for built-in gains and excess net passive income. Form 100S almost always produces an entity-level tax. The 1.5% California S corporation tax is computed on Schedule J of Form 100S, and it’s owed in addition to whatever flows through to shareholders. The minimum franchise tax floor of $800 sits underneath. So the federal return is essentially zero-tax for most S corps and the California return is essentially never zero-tax — that alone changes the workflow.
Second difference: apportionment and allocation. Form 100S has Schedule R for businesses operating in multiple states, where California-source income is computed using single-sales-factor apportionment (with throwback rules for sales not taxed elsewhere). Form 1120-S has no apportionment because federal taxation doesn’t carve income state by state. A California S corp with out-of-state sales has to do real apportionment work on Form 100S that has no federal counterpart. Get the sales factor wrong and the 1.5% base is wrong, and the error compounds across years.
Third difference: California-federal conformity gaps. California does not conform to federal tax law in several meaningful areas — bonus depreciation (California disallows or limits federal bonus depreciation), Section 179 (lower California limits), NOL rules (different carryback/carryforward rules and conformity timing), QBI (no California analog to the federal Section 199A deduction), and various credits. Form 100S has its own depreciation schedules (FTB 3885), its own NOL schedules, and its own adjustments to bridge federal taxable income to California taxable income. Treating Form 100S as a federal copy with the cover page swapped is the most common preparation failure mode we see — and it usually shows up as an FTB notice 18 months later.
Fourth difference: the California Schedule K-1. A California S corp issues both a federal Schedule K-1 (from Form 1120-S) and a California Schedule K-1 (from Form 100S). The two K-1s often have different numbers because of the conformity gaps above. Resident shareholders use the California K-1 to compute their California Form 540 personal tax. Nonresident shareholders use it for their California Form 540NR. Form 100S also reports the PTET election and the per-shareholder PTET credit, which doesn’t exist on the federal K-1 at all. The PTET credit is the workhorse for California-resident shareholders in high brackets, and getting it accurately on the California K-1 — with the right consenting-owner detail — is where Form 100S preparation actually earns its keep.
What is the California S corp franchise tax minimum and when does the first-year waiver apply?
The California S corp franchise tax minimum is $800 per year. The FTB’s S corporations page states that the minimum applies to every S corporation organized in California, qualified to do business in California, or doing business in California, and that the $800 is generally owed even if the corporation is inactive, lost money, or has no California-source income. As long as the entity exists in California, the floor applies. The $800 is the smaller of two numbers — it’s the floor under the 1.5% tax, so a corporation with strong California-source income pays 1.5% of net income instead of $800, and a corporation with little or no California income pays the $800.
The California S corp franchise tax has a narrow first-year waiver. The waiver applies to newly formed or newly qualified corporations filing an initial return for their first taxable year. “Newly formed” means incorporated in California in the year of the return; “newly qualified” means a foreign corporation that registered with the California Secretary of State to do business in California in the year of the return. Either path qualifies for the waiver, but only for the first taxable year. Year two onward, the $800 minimum applies normally.
The most-misread piece of the California S corp franchise tax first-year rule is what it actually waives. The waiver is on the $800 minimum franchise tax, not on the 1.5% S corporation tax. A first-year California S corp with $200,000 of California-source net income still owes 1.5% of that income — $3,000 — to the FTB, even though the $800 minimum is waived. The waiver helps inactive or low-income first-year corporations avoid the floor; it doesn’t help profitable first-year corporations avoid the rate. Reading the FTB S corporations page carefully on this point is worth the five minutes.
The California S corp franchise tax also has a payment-timing quirk that catches new owners. The franchise tax for a given year is generally due by the 15th day of the third month of the year (March 15 for calendar-year filers) — meaning the year-two $800 is due before year one’s return is even filed. That’s because California treats the franchise tax as a tax for the privilege of doing business in the year, paid in advance. Combined with the first-year waiver, the actual cash-flow pattern is: year one, $0 minimum (waiver); year two, $800 due in March of year two (before year one’s return is finished); year three, $800 due in March of year three. The waiver is a one-year benefit, not a permanent break, and budgeting needs to reflect that.
The California S corp franchise tax interacts with dissolution and abandonment. A corporation that fails to formally dissolve with the California Secretary of State continues to owe the $800 minimum, even if the corporation has no operations, no income, and no bank account. We’ve seen owners shut down operations, move on, and discover years later that the FTB has been billing $800 a year plus penalties and interest the entire time. The cleanup is doable but expensive. The right path is to file the final Form 100S, pay any outstanding tax, and file the dissolution paperwork with the Secretary of State — at which point the $800 stops accruing. If you’re winding down a California S corp, do the dissolution properly. If you’re starting one, calendar the year-two $800 the same week you file the formation documents. We handle the structuring side of this in entity formation and structuring.