How do I know if my returns are filed? Can I come back to complete my property tax refund?

Only the IRS and your State control when and if a Federal or State tax refund is Approved and Issued.

Once a tax return has been Accepted by the IRS or a State, TurboTax receives no further information concerning the tax return or the status of any tax refund.

If accepted by the IRS use the federal tax refund website to check the refund status - https://www.irs.gov/refunds

                                                                                                                                 
If accepted by the state use this TurboTax support FAQ to check the state tax refund status - https://ttlc.intuit.com/questions/1899433-how-do-i-track-my-state-refund

After the tax return has been Accepted by the IRS (meaning only that they received the return) it will be in the Processing mode until the tax refund has been Approved and then an Issue Date will be available on the IRS website.

See this IRS website for federal tax refund FAQ's - https://www.irs.gov/refunds/tax-season-refund-frequently-asked-questions

When you log into your TurboTax Online account, your filing status should be displayed on your homepage. You can also use our e-file status lookup tool to get your current status. 

You can also check your refund status directly through the IRS using these links: Where’s My Refund on IRS.gov or the IRS mobile app, IRS2Go to check your status.

Here is a link for you to check the status of your state refund.  State Status

If you have not filed your return(s) you can add your missing data to your return.

If you have already filed your return(s), and you have additional information to add, you will need to file an amended return.