If you have not yet filed your tax return, go back to the taxes section and edit the amount.
If you have already filed you tax return, you will first want to review the return to verify whether you took the Standard Deduction or itemized your deductions. If you took the Standard Deduction, and the discovered error is not large enough to change that decision, do nothing; you are already getting the best refund possible or paying the least tax.
If you itemized deductions or if the error is large enough to make you switch from the Standard Deduction to itemizing, you will need to file an amended 2018 tax return. Please follow the instructions below:
https://ttlc.intuit.com/replies/3288565