Households that share money
Partners, housemates and families who pool costs often agree on a plan but remember it differently. A trail gives everyone the same records to look at and the same questions to ask.
Proof of budget, taught plainly
Every budget line should be able to show its work.
Plumbmark is a small teaching practice for people who plan money and want the plan to hold up. We show you how to tie each planned figure to a source record, a date and a simple check, so that a budget can be explained to a partner, a client or a board without anyone having to take your word for it.
The idea
What a proof of budget is
A proof of budget is the record trail behind a planned number. It answers four plain questions: what the figure is meant to cover, where its basis lives, when that basis was last true, and how someone else could check it. It is not a forecast, and it is not a promise about future income, prices or returns. It is a way of keeping a plan honest about its own assumptions.
Most budgets fail quietly. A figure is typed in once, the reason for it fades from memory, and months later nobody can say whether the number still matches the world. A proof trail does not stop that drift, but it makes the drift visible while there is still time to act on it.
Our teaching
Three promises we keep
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Every line names its source
A planned figure should point to something outside your head: a statement, an invoice, a signed agreement or a dated note. If it points to nothing, that is useful information too. Label it as an estimate and move on.
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Every source carries a date
Records age. A contract from some time ago may no longer describe the bill you pay today. We teach you to write down when each basis was created and when you last compared it with the plan.
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Every number can be re-checked
Anyone you share the plan with should be able to follow the trail in a few steps, without special software and without having to rely on your memory.
Who this is for
Built for people who share or inherit money decisions
Freelancers and small studios
Project costs, tool subscriptions and tax-period estimates change often. A trail shows which numbers are fixed by a signed agreement and which are working estimates that still need a check.
Volunteer boards and clubs
Treasurers often inherit plans they did not write. A trail lets the next person see why a line exists before they decide whether to keep, change or retire it.
Where to begin
Start with the method, then check the evidence
The method takes you through five stages, from a single line to a plan you can revisit: claim, source, date, test and revisit. Each stage leaves a short, dated note. Then read the evidence guide to see which kinds of records prove which things, and which things they cannot prove at all.
A note on what we do not do
Plumbmark publishes teaching material about record keeping. It is not financial, legal, or medical advice. We do not predict prices, recommend investments or assess your personal situation. For decisions with real consequences, speak with a qualified professional who can see your full picture.