The 13th salary scheme

How the "13th Salary" Really Works — and Why It’s Not a Bonus

The "13th salary" was introduced in Brazil during the 1960s and in Portugal in 1974. Today, similar systems exist in various forms throughout Europe and South America. However, in countries like the United States, where employees are often paid weekly instead of monthly, the concept doesn't formally exist.

But how does the 13th salary actually work?

Let’s assume a worker earns $400 per month. Over 12 months, this adds up to:

$400 × 12 = $4,800

In December, this worker receives an extra payment — the so-called "13th salary" — another $400:

$4,800 + $400 = $5,200 per year

At first glance, it appears to be a generous bonus: $400 received without having worked an extra month. But let’s take a closer look.

If someone earns $400 per month, it would be logical to assume they earn $100 per week, since a month is generally considered to have four weeks:

$400 ÷ 4 = $100 per week

Now, here’s the key detail: a year has 52 weeks. So if we calculate the total salary based on weekly pay:

$100 × 52 = $5,200

That’s the same total as the yearly salary including the 13th salary.

What does this mean?

It means that, in reality, the so-called “13th salary” is not a bonus or gift — it’s just money that was effectively withheld throughout the year. Most months are longer than 28 days (four weeks), yet monthly pay does not account for the extra days in those months. A true month has about 4.33 weeks (not exactly four). Over 12 months, those extra days accumulate — adding up to approximately one full extra month of work.

So, when workers are paid monthly instead of weekly, they are essentially underpaid each month by a small fraction. At the end of the year, that underpayment is returned in the form of the “13th salary.”

Therefore, the 13th salary is not a reward, nor is it extra. It’s just part of the regular compensation owed — repackaged.

Final thought:

When politicians claim they’re being generous by offering a 13th salary — or worse, when they threaten to cut it “due to the crisis” — remember that this isn’t a benefit. It’s a deferred portion of your normal pay. Taking it away is the same as reducing your wage.