[#wallet-SelectionResult-GetChange]
= xref:wallet.adoc[wallet]::xref:wallet/SelectionResult.adoc[SelectionResult]::GetChange
:relfileprefix: ../../
:mrdocs:

Get the amount for the change output after paying needed fees.

== Synopsis

Declared in `<wallet/coinselection.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:CAmount.adoc[CAmount]
GetChange(
    xref:CAmount.adoc[CAmount] min_viable_change,
    xref:CAmount.adoc[CAmount] change_fee) const;
----

== Description

The change amount is not 100% precise due to discrepancies in fee calculation. The final change amount (if any) should be corrected after calculating the final tx fees. When there is a discrepancy, most of the time the final change would be slightly bigger than estimated.

Following are the possible factors of discrepancy: + non‐input fees always include segwit flags + input fee estimation always include segwit stack size + input fees are rounded individually and not collectively, which leads to small rounding errors

* input counter size is always assumed to be 1vbyte

== Return Value

Amount for change output, 0 when there is no change.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *min_viable_change* [in]
| Minimum amount for change output, if change would be less then we forgo change
| *change_fee* [in]
| Fees to include change output in the tx
|===


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