Your best bet is to obtain an identity protection PIN (IP PIN) from the IRS. I suggest you go to irs.gov and apply for one online. If you're married, both you and your spouse should get the ID PIN. The caveat is that once you've obtained an ID Pin, you will be using that, instead of your SSN, to file every one of your future tax return. IRS will give you a new ID PIN every year, via email, or you can log back into your IRS account to get it. You will no longer be able to use your SSN to file your returns. Click on this link for details. Save your IRS sign in information.
Get an identity protection PIN | Internal Revenue Service
You may also want to freeze your credit account at all three of the major credit reporting agencies, Experian, TransUnion and Equifax. Make sure you save your sign in information as you will need to unfreeze the accounts whenever you apply for credit.