I am filing taxes foe a start up business, separate from my spouse and personal taxes. Do I claim single to avoid inputting her info

If you are a sole proprietor, all of your income and information goes on the joint return.  You do not file a separate return for the business unless it is an Scorps, Ccorps, or multi-partner LLC.   And, no, you cannot file single if you are legally married.

No, if you are starting up a side business as a single owner, you can still file a joint return with your spouse and report your Business Income/Expenses on Schedule C in your personal return.

You can type 'Schedule C' in the Search area, then 'Jump to schedule c' to get to this section (or find it under Wages & Income).

Here's more info on Reporting Business Income and Expenses, and details on Startup Business Tax Tips you may find helpful.

@ismitchell3