How much money would I owe for turning my taxes a week late from the IRS due date?

It depends.

If you are receiving a refund, there is nothing owed for filing late.

If you owe, and only file a week late, the penalty is minimal. The program will calculate for you.

IRS Definition

A failure to file penalty is charged on returns filed after the due date or extended due date, absent a reasonable cause for filing late.

• The combined penalty is 5% (4.5% late filing and 0.5% late payment) for each month or part of a month that your return was late, up to 25%.
• The late filing penalty applies to the tax that remains unpaid after the due date. Unpaid tax is the total tax shown on your return reduced by amounts paid through withholding, estimated tax payments, and allowed refundable credits.
• If after five months you still haven’t paid, the failure to file penalty will max out, but the failure to pay penalty continues until the tax is paid, up to 25%.
• The maximum total penalty for failure to file and pay is 47.5% (22.5% late filing and 25% late payment) of the tax.
• However, if your return was over 60 days late, the minimum failure to file penalty is the smaller of $205 or 100% of the tax required to be shown on the return.