Child support is never entered on a tax return--not by the person who pays the support nor by the person who receives the child support.
If your GF is the custodial parent of the children--meaning they live with her for at least 183 nights of the year---then she is the one who can claim the children as dependents on her tax return. There are some special provisions that would allow her to sign a form 8332 to let the other parent get the child tax credit for the kids. But the ex cannot claim them for earned income credit, head of household filing status or the childcare credit.
If you and your GF get married, you will have the choice to file married filing jointly or married filing separately. If you are married, her children become your step-children. Step-children can be claimed as dependents on your joint tax return.
This information is for tax year 2022. The "rules" will be same for next year, but the standard deduction amounts will change somewhat.
If you were legally married at the end of 2022 your filing choices are married filing jointly or married filing separately.
Married Filing Jointly is usually better, even if one spouse had little or no income. When you file a joint return, you and your spouse will get the married filing jointly standard deduction of $25,900 (+$1400 for each spouse 65 or older) You are eligible for more credits including education credits, earned income credit, child and dependent care credit, and a larger income limit to receive the child tax credit.
If you choose to file married filing separately, both spouses have to file the same way—either you both itemize or you both use standard deduction. Your tax rate will be higher than on a joint return. Some of the special rules for filing separately include: you cannot get earned income credit, education credits, adoption credits, or deductions for student loan interest. A higher percent of your Social Security benefits may be taxable. Your limit for SALT (state and local taxes and sales tax) will be only $5000 per spouse. In many cases you will not be able to take the child and dependent care credit. The amount you can contribute to a retirement account will be affected. If you live in a community property state, you will be required to provide additional information regarding your spouse’s income. ( Community property states: AZ, CA, ID, LA, NV, NM, TX, WA, WI)
If you are using online TurboTax to prepare your returns, you will need to prepare two separate returns and pay twice.
https://ttlc.intuit.com/questions/1894449-married-filing-jointly-vs-married-filing-separately
https://ttlc.intuit.com/questions/1901162-married-filing-separately-in-community-property-states
https://ttlc.intuit.com/questions/1894449-is-it-better-for-a-married-couple-to-file-jointly-or-separ...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
