Contribution to a traditional IRA then immediately converted to ROTH for 2016 tax year. 1099-R showing taxable distribution of $6500. Can I file 2016-Form 8606 now?

I made a non-deductible contribution to a traditional IRA and converted to ROTH immediately for 2016 tax year.  I didn't include this in the 2016 return and did not file Form 8606.  Can I file 2016 Form 8606 now to avoid paying excess tax?