I've been enjoying this Slate series on how couples manage their finances. There are three methods described in this series: common potters, sometimes sharers and independent operators.
Mr. Sam and I have been, and still are, sometimes sharers since 2004 (when we bought a house together) although our methods have changed over time.
In 2004, we established a joint checking account, what we call our house account, and we each deposited a proportional share into the house account to cover our joint expenses (mortgage, insurance, utilities, etc.). So, the first step was determining how much our joint expenses were. That took a few months to figure out since some expenses fluctuate. Then we each contributed "equal shares" which meant that since I earned more I contributed more. Early on I contributed 2/3 to the house account and he contributed 1/3. I paid all the joint bills out of the house account and we each were responsible for our own individual bills and expenses. The Slate series makes this method seem really complicated and the couples who use this method have a million conversations/debates over what is a joint expense. We didn't struggle with that issue, if the expense related to our home it was a joint expense and came out of our joint account. Also, over time we got into the habit of trading expenses as well, I'd pick up the dry cleaning and pay for it out of my money, Mr. Sam would do the grocery shopping and pay for it out of his money, etc.
After marriage, in 2007 I decided that we ought to pay down all of our unsecured debt (Yay Dave Ramsey) and we undertook an overhaul of our finances. Putting aside the debt issue (another topic) the first step was to create a spending plan (our version of the budget).
Then we decided that since we were now married there would be no "my" money or "your" money anymore and I was, generally, ready to move to the "common potter" method. But, since we had gotten married later in life and we were each used to having our own money and spending it as we wanted we stuck with a modified sometimes sharer method (I'd call it a 90% sharer method).
The 90% sharer method provided that we each deposited all income into our house account. I paid all the bills, joint or individual, serviced the debt (until we paid it off a year later), transferred monies to savings, etc. Then we each received the same amount of money, our "allowance", for day to day spending. We can each spend our allowance as we see fit with no checking in with the other.
This system, with a bit of tweaking each year, has worked well for us since 2007.