How to charge for shop supplies and disposal fees

What actually goes in the shop supplies bucket

The exercise takes one evening and it produces the only figure on this subject that is really yours.

Take a month of receipts and card statements. Pull out every purchase that was consumed doing work but was not billed to a specific job. Chemicals and cleaners. Abrasives and blades. Fasteners, clips and connectors bought in boxes rather than for one car. Gloves, rags and wipes. Tape, wire, heat shrink, cable ties. Small quantities of fluid used for topping up rather than for a service. Sealants and adhesives. Anything you keep in the van because you know you will need some of it this week.

Do not put tools in the bucket. A socket set lasts years and belongs in your overhead or in your rate, not in a per job charge. The test is whether it gets used up. A blade is used up. A grinder is not.

Do not put in anything you already bill directly. Oil sold as part of a service, a filter, a specific part for a specific car: those are on the invoice already and counting them twice is how a fee becomes indefensible.

Now divide the total by the number of jobs you completed in that month. The result is your average consumables cost per job. Do the same for a second month before you rely on it, because one month with a big chemical order in it will mislead you.

Look at the spread as well as the average. If most of the spending is caused by a minority of jobs, an even charge across all jobs is the wrong shape and you may want the charge to scale with labour, or to apply only to the job types that actually consume things. A software installation on a car that never got dirty consumes nothing, and charging it a supplies fee is the version customers complain about.

Recovering it in the rate, or naming it as a line

Once you know your figure, there are two honest ways to collect it, and the choice is more about how you want to be seen than about arithmetic.

Building it into the labour rate is the quiet option. Your rate rises by roughly what the consumables cost per hour of work, and no extra line ever appears on an invoice. The customer sees one price for your time and pays it. Nobody argues about a rate the way they argue about a fee, because a rate is understood to include the cost of doing the work.

The argument against is transparency in the other direction. You lose the ability to point at what a job consumed, and when you eventually raise the rate for real reasons it is doing two jobs at once. Some readers also find that burying it makes them stop tracking it, and an untracked cost drifts.

Naming it as a line is the explicit option. It shows the customer what they are paying for, it lets the charge scale with the job, and it keeps the cost visible to you month after month, which makes it easier to notice when consumable prices move.

The argument against is that any line item invites a question, and a line with a vague name invites a suspicious one. If you name it, name it in plain words, keep it proportionate to what the job really consumed, and be ready to say in one sentence what it covers. A charge you can explain in a sentence almost never becomes a dispute.

What does not work is doing both, or applying the line inconsistently. Charging it to the customers who do not query things and dropping it for the ones who do is not a pricing policy, it is a habit that teaches your best customers that your prices are negotiable and your others that they were overcharged.

One more practical point. If you use a flat amount rather than a proportion, revisit it on a schedule. Chemicals and consumables move with everything else, and a flat figure set two years ago is now recovering less than it did without anybody deciding that.

The disposal side is somebody else invoice arriving at your door

Disposal is not consumables and should not be folded into the same line, because it behaves differently. It is caused by specific jobs, it is a cost somebody else sets, and how it may be handled is regulated in ways consumables are not.

The materials are the familiar ones: used oil and filters, coolant, brake fluid, transmission fluid, batteries, tires, and sometimes refrigerant and airbag components which have their own handling requirements entirely.

A mobile mechanic has a problem a shop does not: you generate the waste at the customer address and carry it away with you. Where it goes next is your responsibility, and the practical answers range from a collection centre that takes some materials from the public, to a dealer or parts store that accepts certain items, to a waste contractor who invoices you.

Price it from what it actually costs you. Get the invoice or the schedule from wherever you take each material, work out the cost per unit you generate, and attach it to the jobs that generate it. A tire job creates a tire to dispose of. A brake fluid flush does not.

Charge it as a pass through and say that is what it is. Disposal is the easiest charge on any repair invoice to explain, because everybody understands that getting rid of five quarts of used oil is not free. Customers who bristle at a vague supplies percentage rarely argue about the line that says what happened to their old tires.

Two things to be careful with. Some materials attract charges that are set by somebody other than you and change without notice, so check the schedule rather than remembering it. And what you may transport, store and hand over, and what documentation goes with it, is governed by rules that vary by state and by material. Find out what applies to you from your state environmental agency or your waste contractor before it becomes a question somebody asks you in an unfriendly context.

Finally, keep the customer old parts question separate from the disposal question. If somebody wants their old components back, they are not asking you to dispose of anything, and the paperwork on the job should say which of the two is happening.