[Koha] Serials and budget control

I can't seem to find a way to mage the serials budget with the serials module in Koha 3.0. It would be great to have serials linked to budget so that we could enter subscription details which include the subscription paid, and have that deduct from a budget in acquisitions. How are other Koha 3.0 libraries managing the serials budget without this feature? Cheers Jo.