Specific to taxes, you can opt-in to the IP PIN program. But that means you have to use the IP PIN every year (the IRS mails you a new one each December) and may be more inconvenience than you want to go through, unless you have already seen fraudulent activity in your accounts.
https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin
If you don't have your IRS online account set up, you should set it up so no one can set one up in your name.
https://www.irs.gov/payments/your-online-account
You can freeze or lock your credit reports (a freeze and a lock are different)--don't forget all 3 credit bureaus.
https://www.nerdwallet.com/article/finance/credit-lock-and-credit-freeze
Update any critical passwords (banks, etc) and don't re-use passwords. Subscribe to a password manager if you need to rather than re-using passwords. Turn two-factor authentication on for any web site where it is offered.
