I know already about the IRS withdrawal if you win the lottery.
But what about at the end of the year income tax filing. In my
Case we have always filed married joint. But now we are retired
With social security and a small pension. But my son is unemployed
Without any income, if he were to cash the lottery ticket, maybe he
Would get more back filing individual.

<moved from Gambling to Taxes>

You must include all your gambling winnings in income on Form 1040, line 21. If you itemize your deductions on Schedule A (Form 1040), you can deduct gambling losses you had during the year, but only up to the amount of your winnings.

Since you are getting SS benefits, a part of it may become taxable if if half of the SS benefits plus your other income exceeds the base amount. The base amount is $25,000 for single, head of household, married filing separately who did not live with the spouse in the year, and it is $32,000 for married filing jointly. For married filing separately who lived with the spouse any time in the year, the base amount is $0.

It WOULD be nice if the AMOUNT of the lottery winnings were disclosed.

If it is $10,000 or less, there may be little effect.

If the winnings exceed $1 MILLION, there are significant issues to be addressed.