UK households spent an average of £676.60 per week in the financial year ending March 2025—9% more in cash terms than the previous year, according to the Office for National Statistics. When incomes differ, dividing that spending equally can leave one person with far less disposable income.
Splitting household costs by income offers another approach. Each person pays the same proportion of shared expenses as the proportion of household income they receive. The right app can calculate or remember those percentages, record payments and maintain a running balance.
The app details below were researched from developer documentation and UK app-store listings on 12 August 2026. Documented features are separated from analysis because an advertised function does not establish whether an app will suit every household.
How proportional bill splitting works
Start with each adult’s regular take-home income. Using net income usually gives you a more practical picture of the money actually available for bills.
The formula is:
Individual income ÷ total household income × 100 = individual contribution percentage
Suppose two partners receive £2,400 and £1,600 per month:
- Total household income: £4,000
- First partner: £2,400 ÷ £4,000 = 60%
- Second partner: £1,600 ÷ £4,000 = 40%
A £1,200 rent payment would therefore be divided into £720 and £480. A £150 energy bill would become £90 and £60.
For a three-person household earning £2,500, £1,500 and £1,000, the percentages would be 50%, 30% and 20%.
This arrangement is not automatically fair in every situation. Unpaid childcare, caring responsibilities, personal debts and large differences in essential personal spending may justify an adjusted ratio. MoneyHelper similarly presents income as one possible factor when deciding how to divide household bills, rather than prescribing a universal formula (MoneyHelper).
Decide what belongs in the shared total
An income-based household budget works best when everyone agrees which costs are genuinely shared.
Common shared expenses include:
- Rent or mortgage payments
- Council Tax or local property charges
- Energy, water and internet
- Groceries and household supplies
- Contents insurance
- Childcare
- Shared transport
- Subscriptions used by everyone
Personal clothing, individual hobbies, personal debt repayments and solo travel will often remain separate. Mixed expenses can be divided differently—for example, household groceries by income but an individual purchase by exact amount.
Review the percentages when someone’s income changes materially. Households with variable or freelance earnings can use an agreed average, such as recent take-home income, and revisit it at regular intervals.
App comparison at a glance
| App | How it handles income-based splits | Best fit | Main limitation |
|---|---|---|---|
| Fairmony | Calculates a two-person split from income shares | Couples with separate accounts | Designed for two partners |
| FairTally | Applies household-defined default ratios | Households with two or more adults | You calculate and enter the ratios |
| Splitwise | Accepts percentages on individual expenses; Pro can save default splits | Couples, families and housemates needing flexible groups | Free accounts have a daily entry limit |
Fairmony: automatic income splitting for couples
Documented functionality
Fairmony is specifically designed for two partners. Its “Smart Split” feature divides expenses in proportion to income, while also supporting 50/50 and custom splits. The developer documents shared balances, recurring expenses, scheduled costs, instalments, reports and multiple currencies (Fairmony).
The UK App Store confirms income-based splitting, partner syncing and manual expense entry without a bank connection. It lists support for iPhone and English, with iOS 16.4 or later required (Fairmony on the UK App Store). The developer’s website also advertises Android availability.
There is a pricing inconsistency worth noting. The website describes the app as free, while the UK App Store lists in-app purchases and says Premium unlocks recurring expenses, instalments and advanced reports. The storefront showed £4.99 and £49.99 purchase options when researched, but the exact plan and renewal period should be confirmed on the purchase screen.
Apple reports that the developer declares no data collection, although Apple expressly says these privacy disclosures are not independently verified. The developer also says income details remain on your devices and no bank link is required (UK App Store privacy disclosure).
Analysis
Fairmony is the most direct match when two partners want the app itself to handle an income-based household expense split. You do not need to convert salaries into percentages before entering each expense.
Pros
- Purpose-built income-based split
- Can remember a couple’s preferred percentage
- Handles recurring household costs
- Does not require access to bank transactions
- Shows shared balances and spending reports
Cons
- Limited to a two-partner structure
- Manual expense entry may require discipline
- Pricing information differs between the developer website and App Store
- The UK App Store did not yet display enough ratings for an overview when researched
FairTally: default ratios for multi-adult households
Documented functionality
FairTally lets a household set its own default ratios based on income, responsibilities or another agreement. It then applies those ratios to shared expenses and maintains running balances. Unlike Fairmony, it supports households with more than two adults (FairTally).
The developer offers web, iOS and Android versions. Its UK App Store listing confirms custom split ratios, category breakdowns, join codes and support for iPhone and iPad running iOS or iPadOS 15 or later (FairTally on the UK App Store).
Full access is free for 30 days, after which the free service becomes view-only. The developer lists monthly household plans starting at $5.99 for two people, while the UK App Store showed local in-app purchase prices beginning at £5.99. Prices increase with household size.
The developer says financial information is encrypted in transit and is not sold or shared for advertising. Apple’s UK listing separately reports that the developer may collect and link names and email addresses to users; as usual, these app-store privacy declarations are developer-supplied rather than independently verified.
Analysis
FairTally is a strong fit for several adults who want one standing income ratio applied throughout the household. It is also more inclusive of household structures that do not fit a conventional two-person couple.
However, FairTally does not calculate the income percentages for you: its developer explicitly says that you set the numbers. Calculate the ratio first, then enter it as the household default.
Pros
- Supports more than two adults
- Applies agreed ratios automatically to later expenses
- Available through a browser as well as mobile apps
- One subscription covers the household
- Keeps category totals and running balances
Cons
- Requires you to calculate the income percentages
- Adding new expenses requires a subscription after the trial
- Pricing rises with household size
- No documented bank import or automated transaction feed
Splitwise: flexible percentages for mixed expenses
Documented functionality
Splitwise supports Android, iOS and the web. When you add an expense, you can divide it equally, by exact amounts, percentages, shares or adjustments (Splitwise split options). It also supports weekly, fortnightly, monthly and yearly recurring entries (Splitwise recurring expenses).
Splitwise does not ask for incomes or calculate an income ratio. You must calculate the household percentages elsewhere and select “Split by percentage” for each relevant expense. A Pro subscription can save a preferred default split so it is applied to new entries automatically.
Free users can add up to four expenses per day. Pro removes that limit and adds default splits, receipt scanning, search, charts and currency conversion (Splitwise Pro documentation). Subscription prices vary by country and plan; the UK App Store listing displays the applicable in-app purchase options.
Splitwise is primarily a shared ledger. You can record an outside bank transfer or cash repayment. Integrated payment options vary materially by country: Splitwise documents PayPal and Venmo integrations for US users, while Pay by Bank is available only in selected European countries. UK users with access to it can settle pound balances with other UK users (Splitwise payment guidance).
Its privacy statement says shared expense information is visible to the selected group and may remain in other members’ records after you delete your account. It also describes collecting registration, device, usage and user-entered expense information (Splitwise privacy statement).
Analysis
Splitwise is the most flexible choice when different expenses need different rules. A household might divide rent 60/40, groceries by income, a restaurant bill by item and a personal purchase by exact amount—all within one group.
It is less convenient for a simple, permanent income split unless you pay for Pro’s default-split feature.
Pros
- Supports couples, families and larger house shares
- Offers percentages, shares and exact amounts
- Handles recurring bills
- Works across mobile and web
- Suitable for households using several splitting rules
Cons
- Does not calculate income shares
- Re-entering the percentage can become repetitive without Pro
- Free accounts are limited to four new expenses per day
- Payment integrations depend on country
- Shared records and personal information are stored online
A practical setup that stays accurate
Whichever app you choose, a simple process reduces mistakes:
- Record each adult’s agreed monthly take-home income.
- Calculate the total and each person’s percentage.
- Round percentages so the household total remains exactly 100%.
- Define which spending categories are shared.
- Enter the percentages as defaults where the app supports them.
- Record who actually paid each bill—not merely who was supposed to pay.
- Use the resulting balance to settle at an agreed interval.
- Recalculate after a significant income or household change.
If one person pays a £100 bill that should be split 60/40, the app should record that person as the payer while assigning £60 and £40 as the final shares. The running balance then reflects the reimbursement required.
Keep income evidence outside the shared app unless everyone genuinely wants it stored there. Most splitting tools need only the resulting percentages, not salary documents or detailed payslips.
Remember that an app does not change legal liability
A household’s internal 60/40 agreement does not necessarily determine who a landlord, council, utility company or lender can pursue. Citizens Advice explains that people are generally responsible for debts in their own name and may be responsible for the whole amount of debts held jointly or subject to joint-and-several liability (Citizens Advice).
Splitwise likewise states that its bills and balances are informal records rather than legally binding contracts (Splitwise terms). Treat any expense-splitting app as an organisational tool, not as a substitute for the underlying bill, tenancy agreement or legal advice.
Conclusion
Income-based bill splitting can make shared costs more manageable when household earnings differ, but the percentage still needs everyone’s agreement. Fairmony provides the most direct automatic option for two partners, FairTally accommodates larger household structures, and Splitwise offers the greatest flexibility when different bills need different rules.
