Fixed vs Variable vs Discretionary Costs:Find Your Floor
Fixed vs variable vs discretionary costs: sort every line into one of three piles and you get your true monthly floor and see where your flexibility lives.
Fixed vs variable vs discretionary: fixed costs continue whatever happens, variable costs scale with activity, discretionary costs are optional. Sorting every line gives you your real monthly floor and shows where the flexibility is. Most people call too much fixed.
Fixed vs variable vs discretionary costs: one question per line
Three words. Everyone nods. Almost nobody sorts honestly.
Here's the whole trick. For each line in your spending, ask one question: what happens to this cost if I do nothing and nothing changes? Then ask a second: what happens if I stop working for a month?
The answers put every line in a pile. The piles are worth far more than the total.
| Pile | The test | Typical lines | Your move when money is tight |
|---|---|---|---|
| Fixed | It continues whatever happens | The domain, the essential subscriptions, anything you've committed to | Cover it first. This is the floor. |
| Variable | It scales with activity | Infrastructure, transaction fees, anything usage-based | Watch it. It rises when you grow and eases when you don't. |
| Discretionary | It is genuinely optional | Whatever you could stop without the business noticing | Stops first. Your flexibility lives here. |
Look at the last column. That's why the fixed vs variable vs discretionary split exists. It's not an accounting exercise. It is a decision order written down in advance.
Fixed: smaller than you think
Fixed costs are the ones that continue whatever happens. The domain. The subscriptions the business genuinely can't run without. Anything you've signed up to for a set period.
Here's the catch. People file things as fixed because they're annoying to cancel, not because they're unavoidable.
"Genuinely fixed" is a high bar. A tool you open twice a quarter isn't fixed. It's discretionary that you've stopped thinking about. A subscription that the business would survive without is a choice, not a law of nature.
The guide's blunt observation is that most people overestimate how much of their spend is truly fixed. Take that as a prompt, not a footnote. Go down your list and challenge every line you've labelled fixed. Would it really keep happening if you did nothing? If you'd shrug and cancel it, move it.
You'll probably find the fixed pile is shorter than the fear.
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Variable costs scale with activity. Infrastructure that grows with your traffic. Transaction fees that rise with your sales. Anything usage-based.
This pile deserves your attention for a different reason from the others. It's the one that rises when things go well. That sounds like a good problem, and it is. But a budget that assumes flat variable costs while you're scaling will be wrong in the most flattering way possible: the better you do, the worse the variance looks.
It also has a quiet advantage in slow months. These costs tend to ease when activity does, so they cushion you without being asked.
One note for later. Variable lines are often forecasts, not allocations. You don't decide a transaction fee, you predict it. Mark those lines accordingly, so that when one moves you know it happened to you rather than because of you. The wider point is in how to read budget variance.
Discretionary: where the real choices are
Discretionary spend is optional. That's all. If the business would go on tomorrow without it, it belongs here.
This is the pile you can change without a hard conversation. It's also the one that fills up quietly, because every individual item seemed reasonable when it was judged alone. That's the problem with deciding one purchase at a time: nothing is ever compared against anything.
Don't treat discretionary as "bad". Some of it will be the most valuable money you spend. Growth often lives here. The point isn't to shrink it. It's that you can see it as a pile, and therefore can choose what goes in it.
When something new tempts you, the pile gives you the right question. What would I stop or defer to fund this? Taking it from discretionary is a decision. Adding it on top is just more spend. That exact moment is dealt with in how to decide whether to buy something for your business.
Fixed vs variable vs discretionary: the number you were after is your floor
Add up the fixed pile. Add the variable lines at a quiet level. Leave discretionary out entirely. That's your true monthly floor.
It's the number that matters in a difficult month. Not your average spend. Not your plan. The cost of staying alive when everything optional stops.
Why is it so useful?
- It tells you what a bad month must cover, so a slow month stops being a fog.
- It shows exactly where to cut first, without a late-night audit.
- It makes the question "can I afford to try this?" answerable, because you know what's untouchable.
- It replaces a vague dread with a figure you can argue with.
For the solo operator that last point is the largest one. Not knowing what you spend produces a background worry far out of proportion to the actual figure. Sorting your costs and finding the floor turns the worry into arithmetic. And the arithmetic is nearly always kinder.
Why a total tells you nothing
Say your monthly bill comes to one figure. You look at it. What do you learn?
Almost nothing. It could be tight or loose, safe or fragile. The total hides the thing you need to know, which is how much of it you can move.
Two businesses can spend exactly the same amount and be in completely different positions. In one, nearly all of it is committed. In the other, most of it could stop tomorrow. The first has no room to manoeuvre. The second has plenty. Same total, opposite lives.
That's why the split earns its place. It turns one number into three, and each of the three tells you what to do. Cover it. Watch it. Question it.
It also helps your scaling plans. When you want to add something new, you can see whether it would land in the fixed pile, where it stays on the bill for good, or in the discretionary pile, where you can drop it again. Commitments you can't undo deserve a harder look than experiments you can.
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Once you've sorted, the budget gets easier to build. The fixed pile is the part you can't argue with, so you allocate it first. The variable pile is partly forecast, so you give it room to move. Whatever remains inside your envelope is the discretionary pile, and now it's a real decision about what to spend it on.
Compare that with allocating from a flat list of twenty-odd items. You'd never notice that one line was a commitment and another a whim. The categories you use for deciding, such as tools, hosting, help and marketing, stay as they are. The three piles sit across them like a second set of labels, and they answer a different question: how hard is each one to change?
How to run the sort on a rainy afternoon
- List every recurring cost. Everything that left your account last quarter and will probably leave again.
- Ask the do-nothing question. Would it continue untouched? If yes, fixed. If it moves with activity, variable. If not, discretionary.
- Challenge every fixed line. Be hostile. Which ones would you actually cancel in a bad month?
- Total each pile. Three numbers. Write them at the top of the page.
- Work out the floor. Fixed plus quiet-level variable.
This slots straight into the wider setup. The full order is in how to set up a budget for a one person business. Sorting is one step of it, and it is the step that tells you most.
Free guide · 19 pagesBudget for a plan that keeps changing.The Budget Playbook: planning spend you will actually follow.Get the free guide →Mistakes to dodge
Calling things fixed because cancelling is a hassle. That inflates your floor and hides your flexibility.
Mixing the piles in one line. A bundle of fixed and optional costs under one label means you can't see either.
Doing the sort once and filing it. Costs migrate. A discretionary tool that becomes essential is now fixed, and you should notice when that happens. The monthly look is the place to catch it.
And finally, using the sort to feel virtuous. The aim isn't to minimise. It is to know which spend is doing which job, so that you decide with your eyes open.
Free assessmentHow trapped are you, really?Take the Corporate Suffocation Index, the free solopreneur readiness assessment.Take the assessment →Frequently asked questions
What is the difference between fixed and variable costs?
Fixed costs continue whatever happens, such as your domain or essential subscriptions. Variable costs scale with activity, such as infrastructure or transaction fees. Fixed is a floor. Variable moves with how busy you are. Fixed vs variable vs discretionary is the three-way split that shows both.
What counts as a discretionary cost?
Anything genuinely optional, meaning the business would carry on without it. It is the first pile to stop in a tight month, and the one where your real choices sit.
How do I find my monthly floor?
Add your fixed costs to your variable costs at a quiet level, and leave out everything discretionary. That total is the minimum the business costs when everything optional stops.
Why do people overestimate their fixed costs?
Mostly because things get filed as fixed when they are merely awkward to cancel. Challenge each fixed line by asking whether it would truly continue if you did nothing. Many turn out to be choices. Run fixed vs variable vs discretionary again whenever a line changes.
The full method, with the checklists, is in The Budget Playbook, a free 19-page playbook.
How trapped are you, really?
Take the Corporate Suffocation Index, the free solopreneur readiness assessment.