I'm not native english speaking. Is the Stipend under the unemployment career the amount of welfare a sim gets each day?

The Careers mod Unemployed module career gives no stipend. It has no hours, no work, no pay, and no chance for advancement. It's a non-career, meant to be a placeholder so that the sims who have it don't get dragged into other positions by SP or by the game itself.

Welfare is paid out, if that SP Money option is used, on a per child basis for households with children that are designated as "Poor" (carrying at least a certain amount of debt, the debt threshold for "Poor" can also be set using SP Money). It doesn't matter if the teen/adult sims in the household have jobs or not. By default though, the Welfare payment is §0 so that means it is not switched on. These settings are under SP > General Options > Options: Money > Options: Fees and Support.

I've had sims with medium to high net worth be in debt because I was having them work on renovations on one of their lots and, since they had children, this triggered the Welfare payments which were totally not necessary. I usually don't engage the option for that reason since it can't be made selective, although I could have just kept giving the money back or transferring to other households who might have needed it.

Ah; I was going of the documentation (Careers-Interactions) where there is an option called 'stipend'. But I see now it is not in the menu in-game.
Thank you for the explanation, that helps.
Follow-up question: All the non-played sims will earn money right? If so won't they always become rich over time even if they earn low wages? Or do they spend money (other then bills) on their own?

Oh, I see. Yes, as the page you linked to says you can actually specify a stipend for the Unemployed career if you wish. I've never done that because I don't want my sims in that placeholder career earning anything just by being in it and they have to be creative to earn money in other ways. If you aren't seeing the option, are you certain that you have the Unemployed module installed in addition to the Careers mod?

Inactives will try to find ways to earn money no matter what their jobs are, or whether they have one or not. They can try to collect, create things to sell, fish, garden/harvest, they can use the Consignment Stores if you have any, etc. SP Money comes with features to charge them daily fees to offset their not having to pay for food or other living expenses, and Unified Billing is what subjects them to Property Taxes (bills twice per week, by default). You can set the Property Tax rates by caste if you wish so that sims with higher Net Worth have to pay higher percentages, and there is even an option for Income Tax.

Between those, things like child support and private school fees, and being able to use GoHere or the Barrier to Entry ticket machines from the TS3 Store to charge for entry into community lots selectively, in some of my worlds the inactives have to work very hard to break even or get ahead financially. I'm easier on them in some of my other worlds.

But without SP and all of these tools to use, the inactives don't have to pay any taxes (bills) at all and their wealth will tend to just keep increasing over time even if they don't have a formal job or profession. That would be great if you are playing households that depend on selling goods or services to the other residents directly rather than rabbithole careers to make a living. But still, many of see the money flows on the inactives as far too unrealistic by EA Standard so we take these extra steps to make it more complicated for them (and us).

Thank you so much for your detailed explanation! This helps me a lot.
And yes, I have the unemployment module installed, although I added it in an existing game, so maybe that is the issue?

Okay, I just took a closer look at this. Indeed there is no Unemployed menu on City Hall under NRaas > Careers, the menu is on the sims. But of course you actually have to put a sim into the mod's Unemployed career in order to see it on them, under NRaas > Careers. This is not the same as "(unemployed)," that means the sim doesn't have an assigned job at all. The mod's Unemployed designation is actually a career that they must sign up for at City Hall or be given by way of MasterController's Choose Job.