Kestrel Bicycle Co. finds out April 15 is two checks, not one — an IRS deadline and a separate New York deadline, on the same day, and New York's own 'quarterly' sales-tax return runs on a different clock entirely

The moment

Kestrel Bicycle Co. is five people in Ithaca, New York: Priya Anand, who opened the shop in 2019 selling and servicing bikes out of a single rented storefront, and four employees — two mechanics, one person running the sales floor, and one handling parts and ordering. Business grew steadily enough that last year Priya's accountant recommended electing S-corp status, and this spring the shop registered with New York to collect sales tax directly rather than routing every sale through a distributor who handled it for her.

It is the last week of September. The bookkeeper who had quietly handled Kestrel's filings since the shop opened retired this summer, and the CPA Priya hired to replace her started by asking a question nobody at Kestrel had ever had to answer directly: what, exactly, is this business on the hook for over the rest of the year, and on what dates? The old bookkeeper had simply paid what needed paying when a bill or a notice showed up. Nobody had ever laid the whole year out in one place.

What they did instead

For years, "taxes" at Kestrel meant a call from the bookkeeper a few times a year saying a payment was due, a number to send, and nothing more. Priya never saw which payment went where. When she pictured her own quarterly estimated tax, she pictured one number, paid once a quarter, that somehow made her square with everyone she owed. That mental model cost nothing while the bookkeeper was covering for it. It was about to cost something the moment Priya had to build the calendar herself.

The questions a CFO asks first

1. Across everything this business actually owes — federal and New York both — what is the very next date, not just April 15, the one date everybody already has memorized?
2. On April 15, is that one payment or two? If it is two, who is each one actually owed to?
3. New York's own sales-tax return is filed "quarterly." Does that mean the same three-month blocks as the income-tax deadlines, or something else?
4. If Kestrel hasn't actually confirmed how often New York wants that sales-tax return filed, does the calendar guess an answer, or say so?

The arithmetic, shown

Three runs, all through the tool's own engine, all on Kestrel's actual profile: an S corporation, five-person payroll, no 1099 contractors, New York added as the state, registered to collect New York sales tax.

Scenario one — the fall calendar, run whole. Every question answered, including a filing frequency New York had in fact already assigned: quarterly. The tool returns twenty dated line items for the year. Two of them are federal annual returns: the S corporation's own Form 1120-S on March 16, 2026 (March 15 is a Sunday) and Priya's Form 1040 on April 15. Three cluster on February 2, 2026 — the federal payroll and wage-statement forms every employer owes regardless of state. The rest are where the two questions above get answered, and neither answer is the one Priya expected.

On the federal estimated-tax dates, New York shows up as its own separate line, not folded into the federal number:

> April 15, 2026 — federal estimated tax, and a separate New York estimated > tax, both due.

> June 15, 2026 — the same pair again.

> September 15, 2026 — the same pair again.

> January 15, 2027 — the same pair a fourth time.

Four dates, eight obligations, not four, and April 15 carries the Form 1040 as a third line. The tool's own note on New York's schedule explains why the state's number is never a guess or a share of the federal one: New York's payments come to an even 25% each quarter, unlike California's uneven split. Two different tax authorities, two different checks, the same due date — easy to see once it is laid out as eight lines instead of one memorized date, and easy to miss when "quarterly taxes" was ever treated as a single number.

The sales-tax side runs on a third, unrelated clock. New York's own sales-tax quarters do not line up with the income-tax quarters above, or with calendar quarters at all:

> March 20, 2026 — covering the December 2025–February 2026 period.

> June 22, 2026 — covering the March–May 2026 period.

> September 21, 2026 — covering the June–August 2026 period.

> December 21, 2026 — covering the September–November 2026 period.

Every one of those four dates falls on a different day than every one of the eight estimated-tax obligations above. "Quarterly" appears on both halves of Kestrel's calendar and means two different three-month windows, filed with different due-date rules, on entirely different days.

Scenario two — the filing frequency nobody had confirmed yet. Run with everything else answered but New York's own sales-tax filing frequency left blank — a real gap, since Kestrel had only just registered and the confirmation letter from the state hadn't arrived yet — the tool does not guess quarterly, monthly, or annual on Kestrel's behalf. It returns a named refusal: missing: ["how often New York has this business file sales tax"]. Nothing about the sales-tax side of the calendar computes until that answer actually exists.

Scenario three — the same shop, run as a corporation instead. Kestrel is not incorporated as a C corporation and has no plan to be, but running the same profile that way shows what would actually change if it were: New York requires a corporation's own first estimated-tax installment, Form CT-300, on March 16, 2026 — the day Kestrel's actual S-corp calendar gives to the federal Form 1120-S, and one that lands before the franchise-tax return itself, which isn't due until April 15. Converting entity types in New York would not just swap which forms apply; it would trade the federal return on March 16 for a New York payment on the same day, and move the federal return, now Form 1120, to April 15.

What changed

Priya's CPA set up two separate reminders for each of the four estimated-tax dates — one federal, one New York — instead of the single "taxes are due" alert the old system relied on, so a payment to one authority is never mistaken for covering the other. The sales-tax frequency question got confirmed directly with the New York State Department of Taxation and Finance rather than assumed, closing the gap scenario two flagged. And the sales-tax dates now sit on the calendar labeled by the actual period they cover — "the June–August 2026 period," not "Q3" — so nobody on Kestrel's team reads a sales-tax deadline and assumes it lines up with the estimated-tax deadline of the same number. None of this changed what Kestrel owes. It changed whether the right amount reaches the right place on the right day, which is the entire content of a calendar.

What the tool will not do

It will not determine whether Kestrel's own sales are taxable under New York law in the first place. That question — whether a specific sale of goods or services actually owes New York sales tax — is not something this tool rules on; it takes the owner's own answer, yes or no, and computes the filing dates that follow from whichever answer is actually true.

It will not cover New York's own fixed-dollar minimum franchise tax, its partnership or LLC filing fee, the metropolitan commuter transportation mobility tax, or the pass-through entity tax — all four are New York obligations that can apply to a business like Kestrel's, and none of them has a single verified figure or rule behind this tool yet. They are named gaps, not computed lines.

It will not cover Tompkins County or the city of Ithaca's own local requirements, if either has any beyond the state sales tax already shown. This tool supports a named, growing list of states — Texas, Florida, Washington, Nevada, Wyoming, California, New York, South Dakota, and Tennessee as of this writing — and local jurisdiction is not one of the things it asks about at all.

It will not know about an extension already filed, a payment plan already in place, or a penalty already assessed on any of these dates. Every line here is the plain, unmodified due date; nothing about a specific filing's own history changes what the tool shows.