If my spouse owes child support for other children will it effect my taxes

if you file a joint return and are due a refund, it might be taken.    

see this thread

https://finance.zacks.com/can-file-married-filing-jointly-spouse-owes-child-support-6506.html

Qualification Guidelines
To qualify as an injured spouse and protect your refund, you have to meet several IRS guidelines. First, the back child support isn't a debt you are legally responsible for. Also, you must have paid federal income tax or claimed a refundable tax credit for that tax year. This could come through withholding from your paycheck if you earned income at a job. If you don't have income, haven't paid any taxes and aren't eligible for tax credits, your share of any joint refund would be zero.

Possibly. If you file jointly, a portion of your refund (if there is a refund) can be garnished to pay the back child support. you can possibly prevent/mitigate this by filing Form 8379, Injured Spouse Allocation for relief. Injured spouses are those who file a joint return and all or part of a refund is garnished/taken to pay the other spouse's debts.

Here are the applicable debts:

• Past-due federal tax

• Child or spousal support

• Federal non-tax debt (such as a student loan)

• State income tax

• State unemployment compensation debts.

File as an injured spouse when:

1) The injured spouse is not legally obligated to pay the past due amount, and

2) The injured spouse meets any of the following conditions:

a) The injured spouse made and reported tax payments, such as federal income tax withholding or estimated tax payments.

b) The injured spouse had earned income (e.g., wages, self-employment income) and claimed the Earned Income Credit (EIC) or the Additional Child Tax Credit (ACTC).

c) The injured spouse claimed a refundable tax credit, such as the Health Coverage Tax Credit

Form 8379 may be filed with the tax return. If the return was already filed, send Form 8379 by itself to the IRS center for the place the injured spouse lived when the return was filed. Attach a copy of all Forms W-2, and W-2G for both spouses, and any Forms 1099 showing federal income tax withholding.

Click here to learn how to file Form 8379 in TurboTax.

Important

Taxpayers in a community property state face additional limitations. Generally, the IRS must first ascertain each spouse's community property share of the overpayment and any separate property to determine how much to refund after an injured spouse claim is filed n a community property state. Since the payments are frequently all community property, this will usually be 50% of the overpayment. See 25.18.5.10 (1), (2), and (3) in the Internal Revenue Manual (IRM) for more details.

@mr-soto0302