Hi Kazim, 

Thanks for reaching out.

Yes you are able to post transactions into a future financial year without closing the current financial year.

Any transactions that you post will go into deferred transactions, you can see these transactions if you go to Nominal > Nominal Deferred Transactions List.

Once you close the current financial year and open the new year, any transactions that fall into the new open period will then move across to the nominal accounts.

Thanks, 

David