Does anyone know why I went from almost 30 years of refunds to having to pay a whole lot? I've always deducted the max from our paychecks to cover taxes.

Yes, 2 dependents becoming independent could certainly have made the difference, particularly if you were previously eligible for child tax credits. Your withholding should have covered the moving up of a tax bracket, but I do suggest making sure you have an updated Form W-4 on file with your employer.

Here is an article you may find helpful that discusses common reasons for owing more tax than expected: Why do I owe taxes?

You may owe taxes to the federal and/or state because your withholding is too low. You can adjust your withholding by submitting a new Form W-4 to your employer.

You can use the TurboTax W-4 Withholding Calculator to help you find the right withholding when completing a new W-4. You can use this info to boost your refund or increase your take-home pay.)

Some of the common reasons why you may owe federal taxes are:

1. You had new sources of income.
2. Your withholding is not enough.
3. You had less charitable contributions.
4. You had fewer medical expenses.
5. You changed filing status (I.e. changing from Married filing jointly to single will cause a jump in your taxes).
6. You had less mortgage interest.
7. You have fewer tax credits, such as Earned Income Credit,, Child Tax Credit, American Opportunity Tax Credit, Lifetime Learning Credit) 
8. The tax brackets changed in 2024 due to inflation, which may pushed you up to a new higher  tax bracket 
9. You worked multiple jobs
10. Your child's age no longer qualifies you for the Credit for Other Dependents or the Child Tax Credit

Click here for "How do I update and print a new W-4?"

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Click here for "Topic no. 202, Tax payment options"