Do you really need to pay for Microsoft 365 extra storage? A buy-vs-reclaim decision guide

Every Microsoft 365 tenant eventually hits the pooled storage ceiling. When it does, the default response is to click the "buy more" button in the admin centre. In most cases that is the wrong answer — not because the add-on is bad, but because the reclaim potential sitting in the tenant is almost always worth more than a year of the add-on fee.

The numbers behind the decision

Microsoft prices SharePoint additional storage at $0.20 per GB per month on the public list rate. That is $200 per TB per month, or $2,400 per TB per year.

Across the tenants we have audited, the median reclaimable fraction is 28% — a quarter of tenant storage is bytes that would never be restored, missed, or opened again if removed. On a 10 TB tenant, 28% is 2.8 TB.

“Keeping 2.8 TB of reclaimable storage online costs $6,720 per year at list rate. A one-week reclaim engagement costs materially less.”— LogiSam reclaim benchmark, 2026

When buying is the right answer

There are three cases where buying additional storage is the correct call:

1. The tenant is new enough that there is nothing meaningful to reclaim — the first 18 months of a tenant are legitimately all new content.
2. The content is heavily regulated and retention policies require everything to stay, even things nobody has opened in years. Buy, label, archive to lower-cost storage via Purview.
3. The reclaimable fraction is small — if a scan shows less than 10% recoverable, you are in a well-governed tenant and the add-on is the simpler path.

When reclaim pays back in month one

The common case: the tenant has 20-40% reclaimable storage sitting in a predictable set of places.

• Second-stage site-collection recycle bins — files deleted months ago that still occupy quota.
• Ex-employee OneDrives — the 30-day retention rule nobody actually enforces.
• Teams meeting recordings — a one-hour meeting is ~400 MB and nobody re-watches most of them.
• SharePoint version history on large files — the default 500 versions is nowhere near what any user has ever restored.
• Duplicates across sites — the same attachment uploaded to Teams, OneDrive and a client site is three copies of the same bytes.

A decision framework in three questions

1. When was the last tenant-wide cleanup? If more than 18 months ago, the reclaim potential almost certainly exceeds a year of add-on fees.
2. How many of the five categories above have been actively managed? If less than three, the reclaim potential is likely 20%+.
3. Is there a Purview retention policy covering more than half the tenant? If yes, buying may be the only legally-safe answer. If no, reclaim is viable.

TSO exists to answer those three questions in one scan. Free, read-only, no card required — the first scan tells you whether reclaim is worth your time before you commit to anything.