Why is the fiscal year called FY24 in some places and FY2024 in others?

Convention. Most US contexts use the calendar year in which the fiscal year ends (FY24 = October 2023 – September 2024). UK and many other countries use the year it starts. The calculator labels both forms.

Does April 6 start the UK tax year?

Yes for personal income tax — a quirk left over from calendar reforms in 1752 and 1800. UK government departments use April 1. The calculator supports both.

How are fiscal quarters numbered?

Q1 is the first three months of the fiscal year, regardless of when that is in the calendar. US federal Q1 is October–December; UK government Q1 is April–June.

configurable start · FY/Q · day-of-FY · live

Fiscal year & quarter for any date

Pick the month your fiscal year starts in (April for India / UK, July for Australia, October for the US Federal government) — get the FY number, quarter and day-of-FY.

Quick Start

How fiscal-year math works

FY is named after its ending year. If the month ≥ start-month, FY = current year + 1. Quarter is offset months / 3 + 1.

01
Pick start month
The month your fiscal year begins.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
startISO 8601RFC 3339epochlive
start · timestampApr · ISO
```
Apr → Mar
```
loaded · ISO 8601zone · ready
02
Decide FY label
If you're in or past the start month, FY = next calendar year.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via Intl.DateTimeFormat.
fyUTC mathIntlDST-safelive
fy · optionsrule · live
```
m ≥ start → +1
```
options applied · UTCDST-safe
03
Compute quarter
Quarter = months-into-FY / 3 (rounded down) + 1.
Output respects the chosen timezone offset (Z vs +05:30) and pads digits per ISO conventions so sorts stay chronological.
quarteroffsetzone-awaresortablepadded
Q · computed1-4 · ready
```
Q1, Q2…
```
computed · instantsortable
04
Day of FY
Diff against FY start in days — useful for FY-relative reporting.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
dayclipboardno oracledeterministicclient-side
✓ · copiedready · done
```
day 152
```
shipped · ready to shipsuccess

Pro tips

Time math without DST landmines

Always store UTC

Convert to local for display only. UTC storage avoids DST jumps and timezone drift in databases.

Watch leap seconds

POSIX time doesn’t count leap seconds; some systems do. Don’t use timestamps for sub-second precision across boundaries.

Prefer Temporal eventually

The Date API has many quirks. Temporal is shipping in modern engines and handles zones correctly.

Cron is timezone-tricky

Cron expressions run in the daemon’s local zone unless told otherwise. Pin a TZ explicitly for predictable runs.

ISO 8601 sorts naturally

YYYY-MM-DDTHH:mm:ss sorts correctly as a string. Don’t use US-style MM/DD/YYYY for anything machine-readable.

Beware Y2K38

Signed 32-bit Unix timestamps overflow in 2038. Use 64-bit storage end-to-end for long-lived systems.

Use Cases

When to compute fiscal year

Finance, ops, reporting.

Quarterly close

Pin a transaction to FY/Q for accounting. Math runs in UTC under the hood to dodge DST jumps — local time is only for display. That means scheduling logic and date diffs survive March / November fall-back without the classic off-by-one-hour bug.

DST-safe

Budget reports

Day-of-FY drives prorated forecasts. Browser clock is the only source — no external time server, no privacy leak, no rate limit. Pair with NTP-synced server time for high-accuracy use cases, but for human-scale work the browser clock is plenty.

UTC-correct

Compensation

FY-aligned reviews and bonuses. ISO 8601 output sorts naturally as strings, perfect for filenames (report-2026-01-15.pdf) and log lines that need chronological ordering without parsing. Drop into S3 keys for free time-bucketing.

ISO-sortable

ETL pipelines

Bucket data into FY/Q without leaving JS. Pairs cleanly with cron, scheduled tasks, and timestamped log analysis. The tool's output drops directly into APScheduler, Linux cron, or GitHub Actions schedule expressions without re-formatting.

spec-grade

Tax planning

India FY ends Mar 31 — calculate cutoffs. Output respects the chosen timezone offset (Z vs +05:30) so REST APIs and database TIMESTAMP WITH TIME ZONE columns round-trip cleanly. No ambiguity between "noon UTC" and "noon local".

zone-aware

Multi-country

Swap start month per subsidiary. Confirms the difference between epoch seconds (10 digits) and milliseconds (13 digits) before you commit code that mis-multiplies by 1000 — a classic bug in cross-language time handling.

epoch-accurate

FAQ

Frequently asked questions

Why is FY named after the ending year?

Convention: 'FY 2026' is the year that closes in 2026, even if it started in April 2025.

Some companies use 4-4-5 weeks?

Yes — retail typically uses NRF 4-4-5 calendars. This tool uses simple calendar months.

Can the FY start mid-month?

Not yet — only whole-month starts.

Is the day-of-FY correct for leap years?

Yes — JavaScript Date counts leap days automatically.

Is anything sent to a server?

No. The math runs locally.

Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

47 in queue·8 shipped this month

Request queued. Thanks!