Redfish Fly & Tackle has thirteen Idaho sales-tax dates in 2026, and no Idaho income-tax date on the sheet at all

The moment

Redfish Fly & Tackle is a fly-fishing shop in Stanley, Idaho. Dale Okafor bought it in 2019. It sells rods, reels, flies and waders from May to October and keeps a thinner shop through the winter, and it has two W-2 employees besides Dale. It is taxed as an S corporation and collects Idaho sales tax at the counter. It is the second of October, the season is ending, and Dale is putting next year's dates on the wall.

What they did instead

Dale's habit was the 20th. Sales tax, the 20th, every month. That is the rule, and for ten of the thirteen dates in the next year it is the right day to file. The habit has two holes. The first is the three months when the 20th is a weekend, where the date moves and a calendar that reads 20th does not. The second is that the 20th is only one of Dale's dates. The owner's federal estimated tax lands on the 15th, the payroll deposits on the end of the month, and in April all three fall inside fifteen days. Nobody had them on one sheet.

The questions a CFO asks first

1. How many Idaho dates does the shop have in the next year, and which of them are not the 20th?
2. What changes if Idaho has the shop on a quarterly schedule instead of monthly?
3. Does any Idaho date land on the same day as a federal one?
4. What does the sheet leave off, and does the entity type change what Idaho adds?

The arithmetic, shown

Eight engine runs, all through the tool's own engine, all built on Redfish's profile: an S corporation, two W-2 employees, no 1099 contractors, Idaho as the state, registered to collect Idaho sales tax.

Scenario one: monthly, the schedule the shop is on. The State Tax Commission's filing page states that

> Most retailers file returns every month. They forward the tax due for each month by the 20th day of the following month.

and for the weekend rule

> If the 20th falls on a weekend or holiday, the return and payment are due on the next workday.

The tool returns twenty-three dated line items. Thirteen are Idaho sales-tax returns, January 2026 through January 2027. The other ten are federal: four installments of the owner's estimated tax, four Form 941 payroll returns, Form 940 and the W-2s. Idaho publishes a rule rather than a dated table, so the tool works each date out. It says so:

> Idaho publishes these as rules (the 20th of the month after the period; 20 days after a quarter; July 20 and January 20; January 20) rather than a dated table, so this tool worked out each date and moved any that fall on a Saturday or Sunday to the next workday, as the Commission's page says for monthly returns.

Ten of the thirteen are the 20th itself. Three are not: June 20, September 20 and December 20, 2026 are a Saturday, a Sunday and a Sunday. The tool dates them

> 2026-06-22

> 2026-09-21

and

> 2026-12-21

all Mondays. The last return, for December 2026, is dated

> 2027-01-20

a Wednesday. The tool is also honest about what it did not check:

> None of these dates is a federal holiday; this run did not check Idaho's own state holiday list date by date.

No Idaho date shares a day with any other item. The crowded day is February 2, 2026, with three federal items (the fourth-quarter Form 941, Form 940 and the W-2s) and no Idaho date on it. But April has the owner's estimated tax on the 15th, Idaho on the 20th and the first-quarter Form 941 on the 30th, three dates in fifteen days.

Scenario two: quarterly. The Commission's page states that

> Retailers who owe less than $750 tax per quarter pay their taxes quarterly. These taxes are due within 20 days after the end of the quarter.

The tool returns fourteen items, not twenty-three, with four Idaho returns, dated

> 2026-04-20

> 2026-07-20

> 2026-10-20

and

> 2027-01-20

Nine fewer lines on the wall, the same ten federal ones. A shop that collects $240 a month collects $720 in a quarter, under the $750 line. A shop that collects $260 a month collects $780, over it. Those two figures are an illustration of the page's wording, not Dale's books. The page does not say which quarter or which year the Commission measures, and the tool does not ask: it asks what schedule Idaho assigned the shop and builds dates from the answer.

Scenario two (b): semiannual. The page states that

> Taxes paid every six months are due by July 20 and January 20.

The tool returns twelve items and two Idaho returns, dated 2026-07-20 and 2027-01-20.

Scenario two (c): annual. The page states that

> Taxes paid once per year are due by January 20.

The tool returns eleven items and one Idaho return, dated 2027-01-20.

Scenario two (d): a schedule the tool does not date. If the shop is on something else, or is not sure, the tool returns ten items: the federal ones only, no Idaho sales-tax date at all. It says

> This tool doesn't compute a specific date for an Idaho sales-tax filing frequency other than monthly, quarterly, semiannual or annual, or one that isn't confirmed.

and sends the owner to the Commission's page and the Taxpayer Access Point account.

Scenario three: the frequency not yet confirmed. With everything else answered and the filing frequency left blank, the tool does not guess. It returns a named refusal: missing: ["how often Idaho has this business file sales tax"]. Nothing computes until there is an answer.

Scenario four: the identical profile as a calendar-year C corporation. The tool returns twenty-four items, not twenty-three. Federal Form 1120 and four Form 1120-W deposits arrive in place of the owner's four estimates. The Idaho side does not move: it is the same thirteen sales-tax returns on the same days. The first corporate federal date is

> 2026-04-15

and the last

> 2026-12-15

and neither is an Idaho date. Idaho adds no estimated-tax line for either entity type, and this is the point of the page. For most states in this tool, changing the entity changes the state's side of the sheet. For Idaho it changes nothing, because the tool has nothing for Idaho except sales tax.

Scenario four (b): the same corporation, tax year unconfirmed. Mark the tax year as not calendar-year, or as unconfirmed, and the tool returns nineteen items. Five federal dates disappear: Form 1120 and the four 1120-W deposits. The thirteen Idaho returns stay. The tool gives the reason:

> This tool only computes Form 1120 and Form 1120-W dates for a calendar-year C corporation (tax year January-December).

What changed

Dale has thirteen Idaho return dates on the same sheet as the federal payroll and estimated-tax dates, and the 20th on the wall is right for ten of the thirteen. The number to watch is three: three returns that a habit of the 20th files on a weekend.

What the tool will not do

It will not decide which schedule the shop is on. Idaho's Commission assigns it, so the tool asks and builds dates from the answer. It will not compute the tax owed on any return. And for Redfish specifically, the sheet is much shorter than the real year. This is the shortest state in the tool, and the tool's own note says so:

> This tool covers only Idaho's state sales-tax due dates. It doesn't cover Idaho individual or corporate estimated payments (the Commission's quarterly schedule was not found on a readable page this run), the corporate return, withholding, pass-through returns (S corporation and partnership), or local option taxes.

That is not a statement that none are due. It is a statement that the tool did not find the dates on a page it could read. Redfish is an S corporation with two employees, so the Idaho pass-through return and Idaho withholding on two people's wages are off the sheet, and the four estimate dates that are on it are the federal ones. A fly shop in a resort town may well have local option taxes too; those are off as well. The tool will not know about an extension, a payment plan or a penalty already assessed on any date above. This tool supports a named list of states, which the state picker in the tool shows, and every line above is the plain due date for the entity type it was told about.