It depends but if you are going to make a significant amount more income from your self-employment business, you will want to increase your taxes paid during the year to make sure that you are not subject to a underpayment penalty when you file your taxes next year.
You can either have your husband's employer withhold more taxes from his wages and/or file estimated tax payments.
Here is a link to the IRS related to tips about estimated tax payments - https://www.irs.gov/uac/newsroom/six-tips-on-making-estimated-tax-payments
