I have 4 children who need to file taxes. Is there a way to do all of them under one account cheaper?

[Bsch4477]

The download or desktop program allows filing for 5 returns. 

[xmasbaby0]

When you use Online TurboTax, you get one return per fee.  Each return needs its own account and user ID.   If you use the same account and user ID for a second return, you overwrite the first one and lose it forever.

https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...

 When you use Desktop TurboTax, which you install from a CD or download to your own hard drive, you can prepare and e-file multiple returns for the cost of the software.  You can e-file up to 5 Federal returns—more if you mail the additional ones.  If you have multiple returns to prepare for family members, Desktop is more cost effective.

Or—-Use this IRS site for other ways to file for free.  There are 8  free software versions available from the IRS Free File site

https://apps.irs.gov/app/freeFile/