Planning on commission: the thin-month method

If you're paid on commission, you already know the problem with averages. Your average month might be comfortable, but you don't live in an average month. You live in a great quarter followed by two slow ones, a big deal that pays out in March and a pipeline that dries up in August. Plans built on the average feel fine until the thin months arrive in a row.

The thin-month method is a simple fix: set your fixed spending to what a thin month pays, and treat everything above it as a lump that goes to a buffer first. This post shows what that does to a year of cash, using RichDue's projection on a realistic sales income.

Why the average misleads

Sales pay usually has two parts: a base salary that arrives on schedule, and commission that arrives after each month or quarter closes, often weeks later. The base is predictable. The commission is not, and it's usually the larger part of total pay.

If you set spending to your average total pay, you're implicitly assuming the good months will arrive in time to cover the bad ones. They often don't. A slow quarter can mean three thin months in a row, and the shortfall compounds: each month starts lower than the last, until the card balance carries what checking can't.

There's also a tax wrinkle. Commission paid separately from salary is supplemental wages, withheld like a bonus at a flat 22% federal rate. (IRS Publication 15, § 7) At higher incomes that can leave the year under-withheld, so a strong commission year can end with a bill in April. Plan with take-home figures, after withholding, and check your bracket.

The example

Here is a sales role with a base salary of $6,000 a month after tax and commission that, after withholding, runs about $6,000 in a typical month, $1,500 in a thin one and $12,000 in a great one. Commission for each month pays out mid-way through the next. Checking holds $15,000.

First, the usual plan: spending set to what an average month pays, rent included.

Worked example

Spending set to an average month

Base salary of $6,000 a month after tax

Commission after tax: $6,000 in a typical month, $1,500 in a thin one, $12,000 in a great one

Spending of $9,000 a month, $15,000 in checking

A typical month: left over

$3,000

A thin month: left over

−$2,280

Lowest balance if every month runs thin

−$12,167

An example, computed with the tax and plan code RichDue runs on your own numbers. RichDue’s low case also spends a little more than usual, as thin months tend to.

In a typical month this works: $3,000 left over. In a thin month the same spending leaves −$2,280. RichDue's low case also assumes you spend a little more than usual ($9,780 rather than $9,000), because the months when income is thin are rarely the months when everything else behaves. If the thin months come in a row, checking runs out in July 2027 and the lowest point is −$12,167: money that would have to come from a card or savings you'd earmarked for something else.

Now the thin-month method: spending set to the salary plus a thin month's commission.

Worked example

Spending set to a thin month

The same pay and the same commission

Spending of $7,500 a month: the salary plus a thin month’s commission

A typical month: to the buffer

$4,500

A thin month: left over

−$555

Lowest balance if every month runs thin

$8,828

Checking in December, typical months

$70,612

An example, computed with the tax and plan code RichDue runs on your own numbers. Before interest on the buffer is spent or moved; RichDue adds 4% a year on cash.

A typical month now sends $4,500 to the buffer. A thin month is close to even, −$555 with the low case's extra spending, and the lowest balance in a year of thin months stays at $8,828. In a year of typical months, checking ends December at $70,612, against $52,279 under the average plan. The commission didn't change. The order did: the buffer gets paid before the lifestyle does.

How to set your thin month

Your thin month is not the worst month on record, and not your average. It's the level you can count on in a slow stretch. Three ways to find it:

1. From history. Take the last 12 to 24 months of commission after tax and sort them. The month a quarter of the way up from the bottom is a reasonable thin month: three in four months pay more.
2. From your plan. If your quota and accelerators are predictable, take what you'd earn at 50–60% of quota, after withholding.
3. From the base. If commission has been truly erratic, or you're new in the role, start with base salary alone and add commission as it proves itself.

Then set your fixed costs to that level. Fixed means the things that arrive whether or not you sold: rent or mortgage, insurance, car payment, childcare, subscriptions, the minimum on any debt.

Where the extra goes

Every month above the thin line produces a surplus. The method only works if the surplus has a job before it arrives. An order that holds up:

1. The buffer, to three thin months. A savings account that covers three months of the gap between fixed spending and a very slow month. In the example, that's what stops checking from going negative.
2. The tax gap. If your commission is withheld at 22% and your bracket is higher, set aside the difference from each check. It keeps April from undoing a good year.
3. Goals with dates. A down payment, a wedding, a car: things with a month attached.
4. Investing. Retirement first, then a brokerage account.
5. Spending on purpose. A great month deserves a small celebration. Decide the amount in advance so it stays small.

Once the buffer is full, the surplus skips step 1 and the plan gets faster.

What to watch through the year

• The lag. Commission earned in March may not pay until April or May. Plan on when it arrives, not when it was earned. A strong quarter that pays late can still leave a thin month in between.
• Clawbacks and draws. If your plan has a recoverable draw or clawbacks on cancelled deals, the buffer covers those too.
• The year-end bill. A big year can push you into a higher bracket than your withholding assumed. Check after each large check, not just in April.
• Lifestyle drift. Three great months make the thin line feel too cautious. Raise it only when a full year of history says the thin month really did move.

If you're new to commission

The first year in a commission role is the hardest to plan, because there's no history and the ramp is real: quotas are often reduced for the first quarter or two, deals take a full sales cycle to close, and the first commission check can arrive three or four months after you start. Start with the base salary as your thin month. Treat every commission check in the first year as a lump: buffer first, then the tax gap, then goals. By the end of the year you'll have twelve months of real figures to set a thin month from, and the buffer will already be in place.

The same applies when a comp plan changes. A new territory, a new quota or a new accelerator schedule resets what a thin month looks like. Go back to the base, let a few quarters pass, and raise the line once the new plan has paid out.

Why a projection helps

The thin-month method is really a question about timing: will checking hold until the next good month? A single average can't answer that, and neither can a spreadsheet of past months. It takes a forward view, month by month, in more than one case.

That's what RichDue's plan does with commission income. It puts the base salary on its pay dates and the commission after each month closes, then shows the next 12 months in low, base and high cases. A shortfall in the low case shows up as a month, before it happens, while there's still time to move money into the buffer.

If your commission arrives as a separate check withheld like a bonus, the bonus take-home calculator shows what a given check leaves after federal, state and Medicare withholding.

Sources

Checked October 30, 2026.

• IRS, Publication 15 (Circular E): commissions are supplemental wages, withheld at the 22% flat rate or with regular wages.
• The income and spending figures are an example. The low case's higher spending and 4% a year on cash are RichDue's default assumptions.

Not tax advice. This is general information about planning on variable pay; your commission plan, your pay stubs and a tax professional are the authority on your own numbers.