There's really two separate issues here:
"We owe too much money when we file our return"
That just means you did not pay enough into the system during the year. You need to adjust your W-4s to claim fewer allowances or have more tax withheld, or you need to make estimated payments, or both.
"We want to lower our tax bill and we have extra money that we don't need to spend on living expenses, but have run out of places to invest the extra that would lower our taxes."
Golly it's tough to be you, isn't it? Remember your 401(k) contribution limit for 2020 is $19,500 or $26,000 if you age 50 or over. If one spouse is not offered a retirement plan at work, a regular or Roth IRA may be an option. The HSA maximum is $7100 for 2020 plus $1000 catchup for each spouse aged 55 or over.
You may want to start looking at investments that will pay you tax-free income, such as state and municipal bonds. You still pay tax on the income from your employer, but you invest it in such a way that the future income stream is tax-free.
You could start making large charitable contributions that would contribute to your emotional and spiritual wellbeing if not your financial wellbeing, and get the itemized tax deduction. When you get ready for bed you can think to yourself, "my mutual fund is up/down another 0.3% today" or "I helped cure cancer/alzheimers/whatever is important to you today."
Basically, if you have so much extra money lying around after paying your living expenses that you've maxed out the easy tax shelters and still have money to invest, it's time to find a real good money manager.
