If by last year you mean your 2019 tax return, you can use it to help you estimate 2020 estimated taxes. Open your return and type estimated taxes for next year in the search box. Click on jump to estimated taxes. Say No to changing your W-4 and continue on from there entering what you think your 2020 income and expenses will be.
You can also use the TurboTax calculator called Taxcaster: https://turbotax.intuit.com/tax-tools/
