It's not a tax proposal, and it's depressing how many people voted thinking it was one.
In Lombardy it's about a list of 23 special topics, which the Constitution says are legislated by both State and regions. The Constitution also says that regions can agree with the central government on getting exclusive legislation on some or all of these topics. There was no need even to have a referendum to start the process. And there is no money on the table, but the president of the region kept mentioning "30 billion euros" which reminds me of the NHS and the British referendum. Not coincidentally, the president is running for reelection in 6 months.
In Veneto the question was simply "would you like more autonomy" without saying what and how. After voting, the president said it's about the 23 topics plus keeping tax money in Veneto. The latter however would require amending the Constitution, which in turn requires either a 2/3 supermajority in both houses, or a simple majority plus a referendum across all of Italy. It's just not going to happen. Constitutional changes have happened in the past, through either a supermajority or a referendum, but this one has no choice of passing. Regardless, a referendum was unnecessary there too.
Both referendums were a huge waste of money, basically amounting to campaigning with public money. They were a farce just like the one in Catalunya, but they were both completely legal and independence from Italy is not on the table anywhere, with the exception of a few nutjobs (equally subdivided among both rich and poor regions).
Addendum: Lombardy played with electronic voting; votes from the opposition were needed to do the referendum, because according to the regional statute referendums need a supermajority, and one opposition party agreed to vote on the condition that voting would be electronic. The president kept boasting about how we would have known the results five minutes after closing the ballot (it takes about three hours to do manual counting), yet 10 hours after we do not even know precisely how many people have voted.