I am not a tax accountant, but I believe that if you routinely pay estimated tax, that you have to pay at least as much tax as you owed the prior year. Tax credits like the EV tax credit or the solar tax credit are extra-ordinary events and you could be penalized for not paying enough estimated tax. However, I think the penalty is small. If the cash flow is more important to you, then ask your accountant how much the penalty is for under paying Estimated Tax based on the prior year rule, but still meeting the current year's tax due.