“I send my mother US$600 a month.” That is the sentence, almost word for word, and the unit in it is already wrong.
US$600 is a decision you made in dollars, sitting where you earn them. Her rent is a bill in reais. The only number that matters is the one at the far end of the wire, and that number moves every month whether you look or not.
What follows is a plan in four moves: size the transfer in reais, hold a buffer on the Brazilian side, set a review date, then choose how the money travels. Every figure below is an example.
I use an example rate of R$5.00 to the dollar throughout. Look up the real one on the Banco Central page first. The buffer has to sit somewhere, so one warning in advance: nothing here is personalized investment advice, and which instrument suits you depends on facts an article cannot know.
Move one: size it in reais, not in dollars
Call her and write down the bills. Not what she says she needs — the actual fixed monthly costs, with due dates. The conversation is uncomfortable for four minutes and then it is the most useful page you own.
| Fixed monthly cost (example figures) | R$ | US$ at example R$5.00 |
|---|---|---|
| Rent (aluguel) | R$1,400 | US$280 |
| Building fee (condomínio) | R$420 | US$84 |
| Health plan (plano de saúde) | R$560 | US$112 |
| Electricity, water, gas | R$230 | US$46 |
| Phone and internet | R$120 | US$24 |
| Recurring pharmacy | R$170 | US$34 |
| Transport pass | R$100 | US$20 |
| Total commitment | R$3,000 | US$600 |
The two totals look interchangeable. They are not. Your commitment is R$3,000. US$600 is merely what R$3,000 happened to cost this month.
Leave one-offs out — a dentist, a new water heater. Variable costs come from the buffer, not from the standing transfer, or the standing transfer drifts upward forever.
What a 10% move does to the same promise
Hold the promise fixed at R$3,000 and let the rate move 10% either way.
| Example rate | To deliver R$3,000 you send | Over twelve months |
|---|---|---|
| R$4.50 (real 10% stronger) | US$666.67 | US$8,000 |
| R$5.00 (example base) | US$600.00 | US$7,200 |
| R$5.50 (real 10% weaker) | US$545.45 | US$6,545 |
That is US$800 a year on or off your budget, from a move of one-tenth. And note the direction, because it catches people: a stronger real is the expensive case for you, which is the opposite of what most senders brace for.
Now run it the other way, fixing the dollar amount at US$600. At R$5.50 she receives R$3,300, so R$300 spare. At R$4.50 she receives R$2,700 — R$300 short of bills that do not negotiate.
Which is the sentence this whole article exists for. Fixing the dollar amount does not remove the currency risk. It transfers it to the person least able to absorb it. How that risk behaves in general is in currency risk when you earn in dollars.
I will not tell you how often a 10% move happens. Scroll the Banco Central historical series and count it yourself — five minutes, free, and you will size the next step differently afterwards.
Move two: keep the buffer on the Brazilian side
Here is the mechanism that makes the plan survive a bad month. You hold a balance in reais, in Brazil, in something with daily liquidity, sized in months of her fixed costs.
Then a bad exchange month is funded from the buffer instead of from a forced FX operation at a rate you hate. The buffer’s real job is to buy you the right to not convert today.
Three months of costs is a reasonable starting point: 3 × R$3,000 = R$9,000, about US$1,800 at the example rate. Build it without a lump sum by adding an example 15% to each transfer — R$3,450 instead of R$3,000, so R$450 a month, and R$9,000 ÷ R$450 = 20 months. At 25% extra it is twelve.
Once it exists, you send the same dollars every month and let the buffer absorb the difference.
| Month (examples) | Rate | You send | Arrives | Buffer moves | Buffer balance |
|---|---|---|---|---|---|
| Starting point | — | — | — | — | R$9,000 |
| Month 1 | R$5.00 | US$600 | R$3,000 | — | R$9,000 |
| Month 2 | R$4.50 | US$600 | R$2,700 | −R$300 | R$8,700 |
| Month 3 | R$5.60 | US$600 | R$3,360 | +R$360 | R$9,060 |
Read the last column, not the middle ones. You keep a fixed dollar outflow, she keeps a fixed reais income, and the volatility lands on a balance instead of on her month.
Give it two trigger levels so you are not deciding by mood. Below one month of costs, raise the dollar amount. Above six, stop topping up and convert less. A number, not a feeling.
Size it against the worst twelve-month stretch in that series, not one bad month: a buffer that only survives an average year is not a buffer. The same logic for your own money is in holding an emergency fund in two currencies.
Move three: the review date, and the cost nobody counts
Set a review every three or six months, and review on the date, not on the rate. Reviewing because the rate moved is just timing with extra steps.
- Her actual bills, because Brazilian rent and building fees reset on an annual index and the old number goes stale quietly.
- The buffer balance and its trend across the last three months, which is the only honest signal about whether the dollar amount is still right.
- The all-in cost of moving the money, as a single percentage.
Now the cost nobody counts. Her bills rise in reais. At an example 5% annual reset, R$3,000 becomes R$3,150 — US$630 at the same R$5.00. Your dollar bill grew 5% with the exchange rate standing perfectly still.
Compound that example 5% over five years: R$3,000 × 1.055 = R$3,828, or US$766 at the unchanged example rate. A rise of nearly 28% in your commitment that no exchange rate caused — which is why the transfer needs a review date.
Move four: how the money travels
Three things make up the cost of turning dollars into reais: the exchange rate spread, proportional to the amount, any fixed fee per operation, and the tax on the FX operation. IOF exists on these operations — check the current percentage yourself, as it is set by rule and revised.
Only one of the three shrinks when you consolidate. Twelve monthly transfers at an example US$5 fixed fee cost US$60 a year; four quarterly ones cost US$20. You saved US$40. Meanwhile an example 1% spread on US$7,200 is US$72 whether you send once or twelve times.
So consolidating cuts the fee and never the spread. But monthly bills need monthly money, which is precisely what the buffer buys you: you can convert quarterly and let her draw monthly. Once reais are in a Brazilian account, moving them to her is a domestic transfer, and Pix — Brazil’s instant payment system — does that in seconds.
Banks, brokerages and specialist currency firms are the three categories. I do not rank them and will not name a best one — turn each quote into one effective percentage and they compare themselves, as in the real cost of money sent to Brazil, line by line.
What to do this week
- Get the real bills from her, in reais, with due dates, and total them.
- Divide that total by the rate you were last actually quoted — not the reference rate — to see what the promise really costs you.
- Choose the buffer size in months and the top-up percentage, and write both down where she can see them too.
- Put the review date in your calendar now, three months out.
- Compute the all-in cost of your current transfer method once, as one percentage.
Whether regular support has any declaration or tax consequence, for either of you, is a question for a contador — a Brazilian accountant. Ask it once, properly, rather than guessing every year. The wider set of decisions is mapped in the guide to earning abroad with money in Brazil.
And the test for whether the plan works is not your spreadsheet. It is this: she should not be able to tell, from her own bank account, what the dollar did last month.