01
Safe to spend today
The number on Tally's first screen. It answers one question: how much can I spend today without putting this week's bills at risk?
left this month= your plan for the month − what you have spent
to live on= left this month − bills due in the next 7 days
safe to spend today= to live on ÷ days left in the month, counting today
- Days left counts today. On the last day of the month it is 1, never 0, so the division always works.
- It never goes below zero. If the week's bills take everything that is left, today reads zero and says why.
- Savings are not in the plan. When you make a plan, what you save is set aside first and never assigned to spending, so the plan is already what you mean to spend. The web instrument starts from what you have instead, so it asks for your savings and takes them off first.
- It is worked out again with every purchase. Spend something and what is left is divided again over the same days. Spend nothing and, unless a bill comes due, tomorrow's number is a little higher: the same money over one day fewer.
- Whole units on the first screen, cents underneath. The first screen rounds to the nearest whole unit. The explanation behind the number prints the same three lines to the cent.
- The morning's figure is kept. Tally also works out what today was allowed before anything was spent today, and measures whether today was a heavy day against that, so the yardstick does not shrink as you spend.
Worked example. A plan of $3,000. On the 10th of a 30-day month you have spent $1,100, so $1,900 is left. Bills due in the next seven days come to $420, leaving $1,480 to live on. Counting today, 21 days are left: $1,480 ÷ 21 = $70.48. The first screen shows $70.
02
The bill reserve
Before the division, Tally takes this week's bills off the top. A bill is reserved when all of these are true:
- Tally knows about it. It is a charge Tally has found repeating in your accounts, or a bill you added yourself.
- It is due from the start of today through the next seven days. A bill due today that has not posted yet still counts.
- It is due before the 1st of next month. Rent due on the 1st belongs to next month's plan, so it is never reserved against the last week of this one.
- It counts as spending. A charge Tally does not count as spending, such as a loan payment, is never reserved. Reserving it would push the number down for a week and jump it back up the morning it posts, with nothing spent in between.
bill reserve= the sum of known bills where start of today ≤ due date ≤ today + 7 days, and due date < the 1st of next month
A bill in another currency is converted at the day's rate before it is added. A bill further out than seven days is still inside the month's plan: it is spread over the days until its week arrives, and then comes off the top.
03
The Score, 1 to 5
The Score answers one question: at this pace, does the month finish inside your plan? It is built from one number, where the month is heading, divided by your plan.
projected spend= spent so far + the larger of (the pace estimate, bills still due this month)
pace estimate= c × at your pace + (1 − c) × what the plan allows
at your pace= spent so far ÷ today's date × days after today
what the plan allows= plan − spent so far, never below zero
c= (today's date ÷ days in the month − 0.10) ÷ 0.55, kept between 0 and 1
Score= the rung for projected spend ÷ plan
Pace alone misleads early in the month: pay rent on the 2nd and the “rate” says you will spend six times your plan. So for the first tenth of the month Tally trusts your plan alone, from about two thirds of the way through it trusts your pace alone, and in between it blends the two. Bills still due this month (the same known bills as the reserve, from today to the end of the month) are a floor, so a careful month with rent due tomorrow does not read as ahead.
| Score | Name | Projected spend against the plan | On this pace you |
|---|---|---|---|
| 5 | Ahead | 85% or less | finish with money spare |
| 4 | On track | over 85%, up to 100% | finish inside your plan |
| 3 | Running hot | over 100%, up to 115% | finish a little over |
| 2 | Over | over 115%, up to 140% | finish well over |
| 1 | Way over | over 140% | finish far past it |
- The names describe the month, never the person.
- A finished month is graded on what happened: what was spent, divided by the plan, on the same ladder.
- Nothing spent yet means nothing to project. Before the month's first purchase, the Score says so in words instead of guessing.
- One finer figure underneath. Behind the 1 to 5 sits a 0 to 100 figure from the same ratio, which is what the 90-day history draws.
05
Currencies
- Every transaction keeps the currency it happened in, for good. A coffee in Copenhagen stays 45 kr. in your history whether you read Tally in dollars or euro.
- Your plan is kept in the currency you made it in and converted only when you read Tally in another. Changing your display currency changes the lens, never the history.
- Thirty-two currencies can sit in one budget.
amount in B= amount in A ÷ rate of A × rate of B
every rate is quoted against the US dollar
- Rates are refreshed once a day from a public exchange-rate feed. If a day's rates fail a check (a currency missing, or any rate moving more than a quarter in one day), the whole batch is refused and yesterday's rates stay.
- These are reference rates, not your bank's. A conversion in Tally can differ a little from what your bank or card charged, which is why the transaction itself always keeps its own amount and currency.
- Amounts are written the way your language writes them: 1,234.50 in English, 1.234,50 in Danish and Dutch, 1 234,50 in French.
06
What Tally never does
- Never sees your bank login. US banks connect through Plaid, read-only. You sign in through Plaid or on your bank's own page, never inside Tally.
- Never moves money. Bank connections are read-only.
- Never sells your data, and never uses it to advertise anyone else's products.
- Never shows your bank balances to your family group. Three switches decide what the others see: your transactions, your budget contributions and your income.
- Never cancels anything for you. Money Finder shows you where to cancel; the decision is yours.
- Never takes a cut of what you save.
- Never guesses an income to split a bill by.
- Never rewrites your history when you change currency.
07
Sources
- Currency codes and minor units (how many decimal places a currency has): ISO 4217, International Organization for Standardization. iso.org/iso-4217-currency-codes
- Everything else on this page is Tally's own rule, written from the app's code. It is not a standard and not financial advice.
Questions about a number? Write to us at [email protected].
— The Tally team