TL;DR
Your cost basis, along with the sale price, determines your capital gains tax. Keep the purchase closing statement, receipts and permits for capital improvements, and documentation of any inheritance, gift, or rental conversion. When basis depends on a past value, a retrospective appraisal can establish it.
Your cost basis determines your capital gains tax when you sell, so the records you keep over the years directly affect what you owe. Basis usually starts with what you paid, plus purchase costs, and adjusts upward for qualifying capital improvements. For an inherited home, the basis generally steps up to the date-of-death value. Keeping the right documentation, and getting a retrospective appraisal when basis depends on a past value, is how you protect yourself from paying tax you do not actually owe.
What records do I need for cost basis?
Keep the purchase closing statement, receipts and permits for every significant improvement, and documentation of special events such as an inheritance, a gift, or a conversion to or from rental use. Each of these adjusts basis, and the IRS standard is documentation, not memory. Organized records are what let you defend the basis you claim.
Routine repairs generally do not adjust basis, while capital improvements generally do, so keep the distinction clear.
How do improvements change my basis?
Qualifying capital improvements, such as an addition, a new roof, or a renovated kitchen, generally increase your basis, which lowers your taxable gain when you sell. That makes improvement records worth real money. Reconstructing decades of improvements from memory is painful and imprecise, so keep the paperwork as you go.
Qualifying capital improvements, such as an addition, a new roof, or a renovated kitchen, generally increase your basis, which lowers your taxable gain when you sell, and when an addition changes your home, getting your new square footage into the record matters.
The homeowners who struggle at sale time are usually the ones who kept nothing.
What if basis depends on a past value?
Some basis questions turn on a value rather than a cost. If you inherited the home, your basis generally steps up to the date-of-death value; if you converted it to a rental, the value at conversion matters. When no appraisal was done at the time, a retrospective appraisal can establish that past value now.
When no appraisal was done at the time, a retrospective appraisal can establish that past value now, exactly the situation in capital gains and selling a long-held home with a retrospective appraisal.
If you inherited the home, your basis generally steps up to the date-of-death value; if you converted it to a rental, the value at conversion matters, the benefit explained in the stepped-up basis tax benefit most heirs don't know they have.
A certified appraisal tied to the correct past date is the documentation the tax treatment requires.
When should I sort this out?
Long before you sell. Keeping records steadily, and commissioning a retrospective appraisal early if you need one, is far easier than scrambling at closing or under audit. The basis you can document is the basis you can defend.
The person who thanks you for good records is the you who signs the closing papers years from now.
Cost basis: what to keep
ItemWhy it mattersPurchase closing statementEstablishes your starting basisReceipts and permits for improvementsCapital improvements raise basisInheritance documentationBasis steps up to date-of-death valueRental conversion recordsValue at conversion affects basis and depreciation
Keep the records now, and get a retrospective appraisal if your basis depends on a past value. The documentation you build today protects you at sale time. Aladdin Appraisal provides retrospective valuations across Greater Boston. This is general information, not tax advice; confirm how the rules apply to you with your CPA.
Aladdin Appraisal provides retrospective valuations across Greater Boston, including retrospective and cost-basis appraisals in Natick and throughout Middlesex County.
FAQ
What records do I need for capital gains when I sell my home?
Keep the purchase closing statement, receipts and permits for capital improvements, and documentation of any inheritance, gift, or rental conversion. These establish and adjust your cost basis, which determines your taxable gain.
Do home improvements reduce capital gains tax?
Qualifying capital improvements generally increase your cost basis, which lowers your taxable gain. Routine repairs generally do not. Keep receipts and permits so you can document the improvements.
How do I establish basis on an inherited home?
Your basis generally steps up to the date-of-death value. If no appraisal was done at the time, a retrospective appraisal can establish that value now, documenting the stepped-up basis.
What if I converted my home to a rental?
The value at conversion matters for basis and depreciation. If it was not documented then, a retrospective appraisal can establish the value as of the conversion date.
About the author: Adam Wiener is the principal appraiser and owner of Aladdin Appraisal, a certified Massachusetts real estate appraisal firm serving Greater Boston across Middlesex, Suffolk, and Norfolk counties. Reach the team at (617) 517-3711 or info@aladdinappraisal.com.
NAP: Aladdin Appraisal | 187 Auburndale Ave, Auburndale, MA 02466 | (617) 517-3711 | info@aladdinappraisal.com | https://www.aladdinappraisal.com | Service area: Greater Boston across Middlesex, Suffolk, and Norfolk counties, MA
This article is general information, not legal, tax, or valuation advice for your specific property. For a formal opinion of value, order an appraisal; for legal or tax questions, talk to your attorney or tax professional.
