You just bought a house. Do this first.

This is not about tax you might owe in fifteen years. It is about a document currently sitting in a folder on your counter, and the fact that today is the cheapest day it will ever be to deal with it.

Your home’s basisstarts at purchase. Everything after that is an adjustment to a number that begins on the day you closed — and the paperwork establishing it is in your hands right now, complete, in one place, for the only time.

Why the first month is different

Ask someone who has owned a home for fifteen years what they paid in transfer taxes at closing, and you will get a guess. Ask them for the settlement statement and you will get a search of three filing cabinets, an old email account and, eventually, a request to their title company.

Ask someone who closed last month, and they will hand it to you.

That difference is the whole argument. The work of establishing basis is not difficult, it is simply spread over decades — and the single largest chunk of it is available to you, right now, in one document you have not yet filed away.

The first two years after purchase are also when most people do the most work on a house. New floors, the kitchen, the boiler that turned out to be older than advertised. You are about to generate exactly the records this is about, at the exact moment you are best placed to keep them.

Start with the settlement statement

Most people assume basis is the purchase price plus renovations. Certain costs from the purchase itself may also belong there, and that is money already spent and already documented (Publication 523, Publication 530).

Your settlement statement is a mix. Some lines may be added to basis, some are deductible in other ways, and some are neither — and the distinction is not obvious from the labels. What matters today is that the document is kept and legible, not that you classify every line correctly this afternoon. Classification can be revisited with a tax professional; a lost document cannot.

Which purchase costs may affect basis goes through the statement line by line.

What to capture

Ten minutes, once:

• Purchase price and closing date. The two figures everything else adjusts from.
• A copy of the settlement statement— a clear photograph is fine. Stored somewhere that is not a single laptop and not an email account tied to an employer.
• The inspection report. Not a basis document, but the list of everything you are about to spend money on, written by someone who looked.
• Anything you paid for before moving in— work done between contract and occupancy is easy to forget, because it does not feel like it belongs to living there yet.

Then the habit

After that it is a few minutes each time you spend money on the house. The five minutes after the contractor leaves, while the invoice is still in your hand and you remember what the work actually was, beats fifteen years of trying to recall it.

Log what was done in words a stranger would understand — “replaced roof, full tear off” rather than “roof” — keep the receipt with it, and let the question of what qualifies be settled later by the person qualified to settle it. Qualifying improvements may raise your adjusted basis and reduce taxable gain when you eventually sell, but only where the cost can be supported.

Whether any of it changes your tax bill depends on facts that will not exist for years: what the home is worth then, your filing status, whether you ever let it out. You cannot know which way that falls. You can decide, cheaply and now, to still have the paperwork when it does.

What basis actually is if you want the five-minute version first.