My wife passed away in 8/2016. I want to file seperatly. But the program says I can't.

[Patrice]

According to IRS publication 17, if your spouse died during the year, you are considered married for the whole year for filing status purposes.  Since your wife died during the year, you are considered married for the whole year for filing status purposes. If you did not remarry before the end of the tax year, you can file a joint return for yourself and your deceased spouse.  

Since your wife died in 2016, you should also file jointly with your late spouse unless you remarried in 2016. In that case, you'd file a joint return with your new spouse and file your deceased spouse's return as Married Filing Separately.

I am attaching the screenshots to show how you would enter the information in the TurboTax program.

For more info please visit: https://www.irs.gov/publications/p17/ch02.html#en_US_2016_publink1000170746