I earned money from a firm in CA in 2015 but didn't file CA state income tax

[Kestrel_C]

For my 2015 tax bill, I used Turbotax to pay my state taxes to MA, my permanent residence.  But in summer 2015 I had earned a one time fee for consulting with a firm in CA, for $2,500.   Earning anything outside my regular paycheck is unusual and I forgot about it and did not include the $2,500 as earnings.  Now in 2020 the state of CA has charged me with not paying state income tax.   I spoke with a CA state tax office advisor who said I should file an amended 2015 return,  acknowledging the $2,500 income  that was earned from a CA firm, and show that I filed and paid MA state tax. 

My question:  can I use Turbotax to file the amended return?  Are there any examples of how to do this?  I do have my version of 2015 Turbotax but it crashes after "No tax form updates at this time" when I hit OK. 

[rjs]

TurboTax no longer supports years earlier than 2016.

[Kestrel_C]

Turbotax doesn't offer support before 2016 -- thanks, now I understand the crashes.  Ok.  Hoes anyone have advice for how to go about doing an amended return?