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# Add a financial year column to a date in Mammoth

> Add a financial year number to each date with Mammoth's Financial Year function: pick the start month, see which year a date falls in, and change it later.
>
> Applies to: Where: View › Describe your transformation › Date, Numeric & Text › Financial Year

**Financial Year** adds a Number column with the financial year each date falls in, such as 2025. A financial year is named by the year it ends in. With a year that starts in October, October 2024 to September 2025 is 2025.

## Add the Financial Year step

1. In the Transform menu, select **Date, Numeric & Text** > **Financial Year**. The Extract Date Part panel opens with a **Year starts in** dropdown in place of **Select date part**. It is set to October.
2. In **Select column**, choose the date column.
3. In **Year starts in**, choose the month your financial year starts, from January to December.
4. Check the hint under the form. It shows the last day of the old year and the first day of the new one, for example "Sep 30, 2025 becomes 2025, Oct 1, 2025 becomes 2026. The year is named by the year it ends in." The date format follows your browser.
5. Name the result column (the default is "Financial year") and click **Apply**.

## How the financial year number is worked out

The result is a whole number with no decimals and no thousands separator, such as `2026`.

- A date in or after the start month belongs to the next year's number.
- A date before the start month keeps its calendar year.
- Choosing **January** gives the calendar year, the same as extracting **Year**.

| Year starts in | 15 Mar 2025 | 15 Jul 2025 | 15 Nov 2025 |
| --- | --- | --- | --- |
| January | 2025 | 2025 | 2025 |
| April | 2025 | 2026 | 2026 |
| July | 2025 | 2026 | 2026 |
| October | 2025 | 2025 | 2026 |

The pipeline card describes the step, for example "Financial year, starts in April (number)". To change the start month later, edit the step and pick another month in **Year starts in**. The value comes from each row's date, so it only changes between runs if the date does.

## Related

- [Work with dates and financial years](https://mammoth.io/docs/learn/clean-and-shape/dates/): shift dates, extract parts and measure gaps.
- [Group dates by month, year or weekday](https://mammoth.io/docs/learn/clean-and-shape/group-by-date/): total by period in a pivot.
- [Column types, IDs, currency and percentages](https://mammoth.io/docs/learn/clean-and-shape/column-types/): how Mammoth sets a column's type.
- [Work with text and JSON](https://mammoth.io/docs/learn/clean-and-shape/text-and-json/): extract text, change case and expand JSON.

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Source: https://mammoth.io/docs/learn/clean-and-shape/financial-year.md · Updated: 2026-11-08