All Stellar accounts must maintain a minimum balance of lumens. The minimum balance is calculated using the base reserve, which is currently 0.5 XLM:
Minimum Balance = (2 + # of entries) * base reserve
The absolute minimum balance for an account is 1 XLM, which is equal to
(2 + 0 entries) * 0.5 base reserve. Each additional entry reserves an additional 0.5 XLM. Entries include:
- Data entries
For example, an account with 1 trustline and 2 offers would have a minimum balance of
(2 + 3 entries) * 0.5 base reserve = 2.5 XLM.
Any transaction that would reduce an account’s balance to less than the minimum will be rejected with an
INSUFFICIENT_BALANCE error. Likewise, lumen selling liabilities that would reduce an account’s balance to less than the minimum plus lumen selling liabilities will be rejected with an
The minimum balance is held in reserve, and closing an entry frees up the associated base reserve. For instance: if you zero-out a non-lumen balance and close the associated trustline, the 0.5 XLM base reserve that secured that trustline is added to your available balance.
Validators can vote to change the base reserve — just as they can vote to change ledger limits and and the minimum base fee — but that’s relatively uncommon. It should only happen every few years. For the most part, you can think of the base reserve as a fixed value. When it is changed, the change works by the same consensus process as any transaction. For details, see versioning.
Last updated Sep. 23, 2020