# Microsoft 365 backup: what Microsoft keeps and what backup costs

URL: https://computecloud.co.uk/microsoft-365/backup/
Last updated: 2026-11-07

> Does Microsoft back up Microsoft 365? What it keeps and for how long, a UK cost calculator for Microsoft 365 Backup, immutability and third-party tools.

Microsoft keeps deleted data for set periods, not for ever, and that isn't a backup. Here is what it keeps, what Microsoft 365 Backup costs in pounds, and how three other tools compare.

## Key points

- **Microsoft keeps deleted data for a limited time, but that isn't a backup.** Deleted email: 14 days by default (up to 30). Deleted files in SharePoint and OneDrive: 93 days.
- **Retention policies and litigation hold** (Business Premium, E3, E5) keep data for compliance; they aren't a quick way to restore it.
- **Microsoft 365 Backup** costs $0.15 per GiB a month, about £0.114 (indicative), billed through Azure. 1 TB is about £116.74 a month, ex VAT.
- **Make backups immutable**, so nobody, not even an attacker with an admin account, can delete them early.

## What does Microsoft keep, and for how long?

Microsoft keeps deleted items for set periods so you can undo mistakes. Teams channel files live in SharePoint, so the SharePoint window applies.

How long Microsoft keeps deleted data:

| Kept for | What |
|---|---|
| 14 days | Deleted email, by default. An admin can raise it to 30. |
| 93 days | Deleted files in the OneDrive and SharePoint recycle bin. |
| 30 days | A deleted mailbox, before it is gone for good. |
| 30 days | A leaver's OneDrive, by default (30 to 3,650). |

Retention policies and litigation hold (in Business Premium, Office 365 E3 and E5, and Microsoft 365 E3 and E5) stop content being permanently deleted, but Microsoft says they are built for export, not mass restore. [See which plans include them](https://computecloud.co.uk/tools/microsoft-365-plans/#t=retention-policies,litigation-hold).

## What is Microsoft 365 Backup, and what does it cost?

Microsoft 365 Backup is Microsoft's own backup for Exchange mailboxes, OneDrive and SharePoint (Teams chats aren't covered). It's a pay-as-you-go add-on for any Business, Enterprise or Frontline plan, billed through an Azure subscription at $0.15 per GiB a month. You choose how long backups are kept: 3 months to 10 years for OneDrive and SharePoint, and up to 2 years for Exchange. Restores are free, and data stays inside Microsoft 365.

### Microsoft 365 Backup cost calculator

The web page has a cost calculator. Enter the total you'll protect (mailboxes with archives, OneDrive and SharePoint) and it shows the cost a month and a year, ex VAT. How it is worked out:

- **Protected data** = users × (mailbox and archive + OneDrive) + SharePoint + deleted items and older versions.
- **Cost** = protected GiB × Microsoft's list price of $0.15 a month. A year is 12 months with no growth, as in Microsoft's own calculator.
- Microsoft lists Microsoft 365 Backup at $0.15 per GiB a month and doesn't publish a sterling price. Sterling figures use the rate Microsoft's Azure price list shows for UK regions (£0.0038 per GB a day, which we treat as per GiB), which Microsoft describes as an estimate. Your Azure invoice converts the US dollar price at Microsoft's monthly exchange rate. Prices exclude VAT.
- We treat GB as GiB, as Microsoft's calculator does, so decimal GB figures overstate the cost by up to about 7%. Restores are free, with no other Azure charges. Prices through a CSP partner or an Azure agreement can differ.

Sizes are in the Microsoft 365 admin centre under Reports › Usage; online archives and second-stage recycle bins aren't in those reports. Include deleted items and older versions in your total: Microsoft bills them too, and publishes no typical figure.

Microsoft 365 Backup cost by amount of data, ex VAT, checked 31 October 2026:

| Data protected | A month (indicative) | A year (indicative) | US list price a month |
|---|---|---|---|
| 100 GB | £11.40 | £136.80 | $15.00 |
| 500 GB | £57.00 | £684.00 | $75.00 |
| 1 TB | £116.74 | £1,400.83 | $153.60 |
| 5 TB | £583.68 | £7,004.16 | $768.00 |
| 10 TB | £1,167.36 | £14,008.32 | $1,536.00 |

Your Microsoft 365 plan is priced separately: see [Microsoft 365 pricing in the UK](https://computecloud.co.uk/microsoft-365/pricing/).

## What is an immutable backup, and why does it matter?

**An immutable backup can't be changed or deleted until its retention period ends, even by an administrator.** It matters because an attacker with an admin account can delete ordinary backups before striking.

Microsoft 365 Backup is partly immutable: backups can't be altered, but an admin can delete them by offboarding (with a 90-day undo) or shorten how long they're kept (after 30 days).

**Ask any provider:**

1. Can anyone, including our admins, delete backups or shorten retention early?
2. Do deletions need a delay or a second approver, and can they be undone?
3. Can we restore an older, clean copy if recent backups are encrypted?
4. How are we alerted to mass deletions, even if our systems are compromised?

These follow the NCSC's [Principles for ransomware-resistant cloud backups](https://www.ncsc.gov.uk/collection/ransomware-resistant-backups/principles-for-ransomware-resistant-cloud-backups) (November 2024).

## How do Microsoft 365 Backup, Acronis, Spanning and Veeam compare?

Third-party backup software can keep copies outside Microsoft's service. This compares three on facts from each vendor's own pages. It doesn't rank them or show prices.

What each product's own documentation says, checked 31 October 2026. The products: Microsoft 365 Backup (Microsoft's own add-on); Acronis (Acronis Cyber Protect, Microsoft 365 backup); Spanning (Spanning Backup for Microsoft 365); Veeam Backup (Veeam Backup for Microsoft 365, software you run); Veeam Data Cloud (Veeam Data Cloud for Microsoft 365, run by Veeam).

| What we checked | Microsoft 365 Backup | Acronis | Spanning | Veeam Backup | Veeam Data Cloud |
|---|---|---|---|---|---|
| Backs up | Exchange, OneDrive, SharePoint; Teams channel files, not chats | Exchange, OneDrive, SharePoint, Teams | Exchange, OneDrive, SharePoint, Teams | Exchange, OneDrive, SharePoint, Teams | Exchange, OneDrive, SharePoint, Teams; Entra ID on Advanced |
| Where backups are stored | Inside your Microsoft 365 tenant | Acronis Cloud, or Microsoft 365 Backup Storage | Spanning's own cloud, on AWS | Your own storage, on-premises or cloud | Veeam-run Azure storage, or Microsoft 365 Backup Storage |
| Can backups stay in the UK? | Follows your tenant's residency; UK not named | Yes, UK data centres; you choose the region | Product page lists the UK; help article doesn't | Yes, if your own storage is in the UK | Yes, UK South is a listed region |
| Can backups be made immutable? | Partly: can't be altered, but admins can delete | Yes, says its product page; confirm for your edition | Not stated | Yes, on object storage, set when created | Yes, built in |
| How you buy it | Pay-as-you-go through an Azure subscription | Direct, or through a service provider | Direct, or through partners and MSPs | Online, resellers or Veeam service providers | Veeam partners or Azure Marketplace |

Listed in alphabetical order after Microsoft's own product; inclusion isn't a recommendation. Checked against each vendor's documentation on 31 October 2026. Vendors change their products often, so confirm before you buy.

## Frequently asked questions

### Does Microsoft back up Microsoft 365 data?

Not as a backup you control. Microsoft lets you recover deleted items for set periods: 14 days for email by default and 93 days in the SharePoint and OneDrive recycle bins. To go back further, or recover from a mass deletion, you need a backup such as Microsoft 365 Backup or a third-party tool.

### Is Microsoft 365 Backup included in Business Premium or E5?

No. It's a pay-as-you-go add-on for every Business, Enterprise and Frontline plan, billed through an Azure subscription at $0.15 per GiB a month (about £0.114, indicative), ex VAT. Business Premium and E5 include retention policies and litigation hold, which keep data but aren't a backup.

### Will my backup tool stop working when Microsoft retires EWS?

It might. Microsoft turns off Exchange Web Services in Exchange Online for good on 1 April 2027, and backup tools that still use it are affected. Ask your vendor whether its Exchange backup uses Microsoft Graph. ([Exchange Web Services retires on 1 April 2027](https://computecloud.co.uk/microsoft-365/licensing-changes/#2027-04-01-exchange-online-ews-retirement))

### Is Office 365 backup the same as Microsoft 365 backup?

Yes, in practice. Office 365 E1, E3 and E5 use the same Exchange Online, SharePoint and OneDrive as Microsoft 365 plans, so Office 365 backup software protects them the same way, and Microsoft 365 Backup is an add-on for them too.

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