How to Budget as a Couple with a Joint Account

Moving in together raises a money question that a single budget never had to answer: who pays for what? Rent, groceries and the electricity bill belong to both of you, while your salaries, your hobbies and your savings goals usually stay personal. A joint account for the shared costs is the most common answer, and this tutorial builds one step by step.

Why a Joint Account for Shared Costs

Couples tend to drift into one of three setups. Some pool everything into one account, which is simple but leaves no room for personal spending without a conversation. Others keep everything separate and settle up with transfers whenever one person paid the rent or the big grocery run, which turns every month into a round of bookkeeping.

The joint account sits in the middle. Each partner pays a fixed amount into it every month, and the shared bills leave from there. Everything that is left on your own account is yours to spend or save as you like. Nobody has to keep a list of who paid for the last pizza, and the shared bills are covered on the day they are due.

Our example couple is Anna and Ben. Anna earns 4180 a month after tax, Ben earns 3460. Their shared costs are rent (1890), groceries (640) and utilities (168), which adds up to 2698 a month. They plan to put 2780 into the joint account, so a small buffer builds up for the odd unexpected household cost.

Step 1: Your Salaries and Your Own Accounts

Start with a new budget and add the two incomes. On the budget page, click + Flow, type Anna's Salary as From and Anna's Account as To, keep the type Fixed amount, and enter 4180 with the interval monthly. Both names are new, so BudgetFlow creates them as you type. Repeat the same for Ben with 3460.

Nothing is shared yet, and that is intended. Each salary arrives where it does today, on the personal account of the person who earns it.

Step 2: Split the Contributions by Income

The simplest split is half each: 1390 from Anna and 1390 from Ben. Since Anna earns more, an even split leaves Ben with a much smaller share of his income for himself. Many couples prefer to split shared costs in proportion to income, so that both partners pay the same percentage.

You do not need a calculator for that, because the amount of a flow can be a formula. Add a flow from Anna's Account to Joint Account and enter this amount:

2780 * 4180 / (4180 + 3460)

That is the 2780 for the joint account, times Anna's share of the combined income (4180 out of 7640, about 54.7%). It comes to about 1521. Ben's flow uses the same formula with his salary on top:

2780 * 3460 / (4180 + 3460)

That gives about 1259. Together the two contributions add up to exactly 2780, and each partner pays about 36.4% of their income. When one of you gets a raise, you update the salary in both formulas and the split adjusts by itself.

Step 3: Pay the Shared Costs from the Joint Account

Now the joint account needs somewhere to send its money. Add three fixed flows that start at Joint Account: 1890 to Rent, 640 to Groceries and 168 to Utilities, all monthly.

At this point the ⚠ next to the budget title shows an issue, because the joint account receives 2780 and only pays out 2698. The 82 that is left would sit in the account without a plan. Instead of calculating that number yourself, add one more flow from Joint Account to Household Reserve and pick the type Send excess cash. This smart flow has no amount of its own: it takes whatever the joint account has left after all other flows, which is 82 here.

The reserve covers the costs that never fit a monthly plan: a new kettle, a repair, the deposit for a parking spot. If your rent goes up next year, you change the rent flow and the reserve shrinks by the same amount without any other edits.

Step 4: Personal Spending and Personal Savings

What remains on each personal account belongs to its owner. Anna plans 1150 a month for her own spending, Ben plans 980. Add those as fixed flows from each personal account to Anna's Spending and Ben's Spending.

The rest should go to savings, and again a smart flow does the arithmetic. Add a flow from Anna's Account to Anna's Savings with the type Send excess cash, and the same for Ben. Anna's savings flow carries about 1509 (4180 minus 1521 minus 1150), Ben's carries about 1221 (3460 minus 1259 minus 980).

Here is the complete list of flows in this budget:

• Anna's Salary → Anna's Account: 4180 monthly
• Ben's Salary → Ben's Account: 3460 monthly
• Anna's Account → Joint Account: 2780 * 4180 / (4180 + 3460) monthly (about 1521)
• Ben's Account → Joint Account: 2780 * 3460 / (4180 + 3460) monthly (about 1259)
• Joint Account → Rent: 1890 monthly
• Joint Account → Groceries: 640 monthly
• Joint Account → Utilities: 168 monthly
• Joint Account sends excess cash to Household Reserve (82)
• Anna's Account → Anna's Spending: 1150 monthly
• Ben's Account → Ben's Spending: 980 monthly
• Anna's Account sends excess cash to Anna's Savings (about 1509)
• Ben's Account sends excess cash to Ben's Savings (about 1221)

Switch the interval select at the top to yearly and the same budget shows what you pay into the joint account over a whole year: about 18252 from Anna and 15108 from Ben, against 22680 for rent alone.

Doing It Together as a Shared Budget

The budget above lives in one account, which is fine when one of you does the planning. If you both want to see and edit the household part, turn it into a shared budget.

One partner creates the household budget from the budgets list, with the joint account and its costs. Next to that budget in the budgets list, click Invite and enter the email of the other partner. After they accept the invite, the budget appears for both of you.

Each of you then opens the shared budget's settings and clicks Share an account to share your own account, the one that pays into the joint account. With both personal accounts shared, either partner can add or edit the contribution flows into the joint account.

Sharing an account does not reveal the rest of your finances. Members of a shared budget see only the shared accounts and the flows between them. Anna's spending, Ben's savings and every other part of your personal budgets stay private. If you want to see the whole route of your money in your own budget, including the part that runs through the household, turn on Show flows inside shared budgets in your personal budget's settings.

Build It with Your Own Numbers

You can build this budget in about ten minutes with your own names and numbers. Put in your two salaries, replace the 2780 in the contribution formulas with your own shared costs, and the smart flows take care of the reserve and the savings.