## Documentation Index

Access the complete documentation index at:
https://www.zoho.com/uk/books/kb/llms.txt

Use this file to discover all available documentation pages before proceeding.

[Back](./)

# Can I change the Period Type and Tax Basis after I submit my first Quarterly Update?

 ![](/books/images/ue-resources/llm-utility-menu/sparkle-ai.svg) Explore With AI ![](/books/images/ue-resources/llm-utility-menu/dd-arrow.svg) 

*   [Open in ChatGPT (opens in new tab)](https://chatgpt.com/?prompt=Analyze+the+content+of+https%3A%2F%2Fwww.zoho.com%2Fuk%2Fbooks%2Fkb%2Fmtd-it%2Fchange-period-type-after-first-quarterly-update.html+and+understand+it+thoroughly+so+I+can+ask+questions+about+it.)
*   [Open in Claude (opens in new tab)](https://claude.ai/new?q=Analyze+the+content+of+https%3A%2F%2Fwww.zoho.com%2Fuk%2Fbooks%2Fkb%2Fmtd-it%2Fchange-period-type-after-first-quarterly-update.html+and+understand+it+thoroughly+so+I+can+ask+questions+about+it.)
*    ![Copy for LLM](/books/images/ue-resources/llm-utility-menu/copy.svg) Copy for LLM
*    [![View as Markdown](/books/images/ue-resources/llm-utility-menu/md.svg) View as Markdown (opens in new tab)](/uk/books/kb/mtd-it/change-period-type-after-first-quarterly-update.md)

You can change the **Period Type** only before submitting the first Quarterly Update for a tax year. HMRC locks it after the first submission. You can change the **Tax Basis** until you submit the last Quarterly Update. HMRC locks it after the last submission.

Before submitting an update, verify these values in the _Send Quarterly Update to HMRC_ pop-up. If they’re correct, click **Send Update**. If the **Period Type** is incorrect, click **Cancel** before submitting the first update. Delete any existing quarterly updates, then [fetch the obligations again](/uk/books/help/mtd-it/quarterly-updates.html#fetch) with the correct **Period Type** and **Tax Basis**. Verify the values before submitting.