> ## Documentation Index
> Fetch the complete documentation index at: https://docs.denari.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Periods

> A period is a named stretch of time, and everyone points at the same one.

**A period is a named stretch of time, and everyone points at the same one.** *Sep 2026*, *Q3 2026*, *FY2025*. It has a start date and an end date. That is all it is.

Projects are the dated jobs. Invoices are the bills. When a project says *September 2026 bookkeeping* and an invoice says *September 2026*, they point at the exact same September 2026. That's what lets work and billing line up without anyone matching dates by hand.

## Things to know

* **Nobody types periods in.** Flows makes each period the first time something needs it, and reuses it after that.
* **One per firm.** There is only one *Sep 2026* for your whole firm, shared by every client.
* **A period has no status.** It is never open or closed by itself. The statuses on the billing side belong to one billing group's billing of that period, not to the period. See [Billing periods](/flows/billing-periods). Locking a bill never locks the work.
* **Fiscal years.** For yearly work, the period can follow a client's fiscal year instead of the calendar year.

## Dates come from periods

Most dates in Flows are counted from a period:

* *25 days after the period ends*
* *on April 15*
* *2 weeks before the period starts*

This is why one setup gives the right dates every time. Point the same rule at September and you get September's dates. Point it at October and you get October's.

<Accordion title="A small example">
  A firm does monthly bookkeeping for Acme and a quarterly review for Beko.

  * Acme's September bookkeeping points at the month period **Sep 2026**.
  * Beko's Q3 review points at the quarter period **Q3 2026**.
  * When Acme is billed for September, that invoice points at the same **Sep 2026**.
  * **Sep 2026** and **Q3 2026** are each one shared period, reused everywhere they apply.
</Accordion>

<Note>
  The period a piece of work belongs to and the period you bill it in are set
  separately, and they're allowed to differ. See [The two
  clocks](/flows/billing#the-two-clocks).
</Note>


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