Get your taxes done using TurboTax

What threshold for filing a joint return are you talking about?   There is no income threshold that prevents you from filing jointly.   

As for your wins and losses---- the losses have no effect at all unless you have enough itemized deductions to exceed your standard deduction.   Losses are an itemized deduction, just like mortgage interest or property tax, etc, so unless you have enough itemized deductions your losses will not offset the winnings at all.

https://www.irs.gov/help/ita/how-do-i-claim-my-gambling-winnings-and-or-losses

Gambling winnings are taxable income.  Losses are an itemized deduction.  If you do not have enough itemized deductions to exceed your standard deduction, your losses will have no effect.

https://blog.turbotax.intuit.com/income-and-investments/how-are-gambling-winnings-taxed-8891/

https://ttlc.intuit.com/questions/1900352-can-i-deduct-my-gambling-losses

2021 STANDARD DEDUCTION AMOUNTS

SINGLE $12,550  (65 or older + $1700)

MARRIED FILING SEPARATELY $12,550  (65 or older + $1350)

MARRIED FILING JOINTLY $25,100  (65 or older + $1350 per spouse)

HEAD OF HOUSEHOLD  $18,800  (54 or older +$1700)

Legally Blind + $1350

And.... the child tax credit:

From this IRS site:

https://www.irs.gov/newsroom/child-tax-credit-most-eligible-families-will-automatically-receive-mont...

Who should opt out or unenroll?

Instead of receiving these advance payments, you may prefer to receive the entire credit when you file your 2021 return. The Child Tax Credit Update Portal enables you to quickly and easily do that. If you make this choice, you will either receive a larger refund or have a smaller amount due when you file.

The unenroll feature can also be helpful to any family that no longer qualifies for the Child Tax Credit or believes they will not qualify when they file their 2021 return. This could happen if, for example:

• Your income in 2021 is too high to qualify you for the credit.
• Someone else (an ex-spouse or another family member, for example) now qualifies to claim your child or children as dependents.
• You live overseas during most or all of 2021.

And some information on filing jointly or separately:

If you are legally married at the end of 2021 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 $25,100 (+$1300 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...