Hi marypeace,
That might not be that easy because you would have to repost transactions.
What might work is if you calculate account-findim balances for the first half of the year and them create a GL journal where you bring them back to zero.
Once this is done, you activate budget control and post the account-findim balances in again.
This works fine as long as you don't have budget overruns already.
Also, this requires quite some work for the balance calculation and posting.
You might want to ask a developer for some help.
Another alternative I could think of is reducing your budget balances that you activate.
Let's say you have a budget of $50000 for travel expense but already spend $30000 in the first half of the year.
Then reduce the budget to the remaining $20000 and activate this one.
Best regards,
Ludwig