The Illinois Pass-Through Entity (PTE) tax credit can be a bit tricky to handle in tax preparation software, as not all software programs handle the flow of this credit correctly from the K-1 to the IL-1040. I had a lot state PTET and all of the software does not support as they are retro and need a lot coders overtime.

You can, however, amend and update the entity K-1 and then amend your 1040 tax return to flow though that credit.

Here’s a general approach to ensuring that the PTE tax credit flows through correctly:

• electronically using MyTax Illinois or ACH Credit or
• by mail using Form IL-1065-V, Payment Voucher for Partnership Replacement Tax, or Form IL-1120-ST-V, Payment Voucher for Small Business Corporation Replacement Tax. 

https://tax.illinois.gov/content/dam/soi/en/web/tax/research/publications/pubs/documents/pub-129.pdf