<p>Is there a way to alter the precision of an existing decimal column in Microsoft SQL Server?</p>

```
```
ALTER TABLE Testing ALTER COLUMN TestDec decimal(16,1)
```
```
Just put
```
decimal(precision, scale)
```
, replacing the precision and scale with your desired values.
I haven't done any testing with this with data in the table, but if you alter the precision, you would be subject to losing data if the new precision is lower.