Does the standard deduction apply to all income including savings account interest income?

[Mike9241]

the standard deduction is not dependent on the type of income.  so yes. 

[Critter-3]

If you are a dependent ...

For 2021, dependents who have earned income more than $12,550, must file their own return. Furthermore, dependents who have unearned income, such as unemployment, interest, dividends or capital gains, will generally have to file their own tax return if that income is more than $1,100 for 2021.

If the earned income is less than $12,550 then the standard deduction is limited to the earned income + 350.   Unearned income in excess of the $350 threashold can trigger the "kiddie tax" rule. 

[NCperson]

for clarity and completeness - as the filing requirements above may unintentially infer that dependents can file on their parent's return....

If you are a dependent ...

For 2021, dependents who have earned income more than $12,550, must file their own a tax return. Furthermore, dependents who have unearned income, such as unemployment, interest, dividends or capital gains, will generally have to file their own a tax return if that income is more than $1,100 for 2021. 

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Also, if there is earned income on a 1099-NEC that exceeds $400 dependents must file a tax return. 

If the earned income is less than $12,550 then the standard deduction is limited to the earned income + 350.   Unearned income in excess of the $350 threashold can trigger the "kiddie tax" rule. 

While there is no requirement to file a tax return if the earned income is below the limits noted above, if there are withholdings, the only way to obtain the refund for those withholdings is to file.  

State filing rquirements may vary