@economista, the above posters are correct. You just have to have a federal tax liability that the EV credit can offset.
Take a look at your Form 1040 from last year. The amount on line 11 is your tax liability. The EV credit, if you had bought the car last year, would go on line 12 and be subtracted on line 13. Notice the "if less than zero, enter zero" part on line 13. That means that it's a use it or lose it credit.
The child tax credit has two parts to it. Part of it also would go on line 12. This part would be combined with the EV credit on your return this year and is also a use it or lose it credit. The second part is refundable and would go on line 17, meaning you would get that money no matter what, even if you don't owe taxes.
...
Just eyeballing things, if your tax withholding was ~$9K and you got a $125 refund, then you probably owed about $9K in taxes last year. If your husband leaves his job this fall, that will lower your income a bit, which will lower your taxes owed a bit, but my guess would be that you'd still owe enough to get the full EV and CTC credits.
Roughly speaking, you'll owe $6,502 less in taxes in 2019. An easy way to roughly estimate how to change your exemptions is to divide that $6,502 by the remaining number of paychecks this year. Keep in mind that you might want to subtract one if your payroll department needs some lead time to make the change. Take that amount and subtract it from whatever amount they're currently withholding from your paycheck to get your new target. Then go to paycheckcity.com and use their calculators to see how many exemptions you'll need to claim in order to get close to that amount. You can also enter an additional dollar amount per paycheck to withhold to gain finer control over your withholding if you want to dial it in that closely.
