Basically in a nutshell, when self employed (as your husband is) you don't "FILE" anything quarterly. You "PAY' estimated taxes quarterly. Then you *file* your annual tax return (joint in your case) annually as you always have.
A good rule of thumb is to send the IRS *AT LEAST* 20% of your *gross* business income each quarter. Then come tax filing time you'll be fine.
Now if your state also taxes personal income, then you'll need to pay quarterly taxes to your state completely separate from your federal quarterly payments. If you send your state a percentage of the business income that is equal to your state's tax rate, then you'll be fine with state taxes at tax filing time too.
