Which comp adjustments actually move a price
Every adjustment you make is a claim about what buyers in this market pay for one specific difference. Most CMAs adjust for too many things, by amounts nobody can justify, and end up less accurate than the raw sale prices they started from.
The rule that governs all of it
An adjustment is worth making when the market demonstrably pays for the difference, and worth skipping when it does not. The test is not "is this different?" — it is "would a buyer have paid more for this, here, this year?" A third bathroom moves a price in most markets. A different shade of siding does not, however different it looks.
Where you can, derive the amount from paired sales: two sales alike in everything but the feature you are pricing. In practice you will rarely find a clean pair, so most adjustments are informed estimates — which is fine, provided you can say where the estimate came from and it is consistent across the report.
The adjustments that usually matter
Living area
Almost always the largest single adjustment, and the one most often done badly. Do not use the full price per square foot of the comp: that figure includes the land, the garage, the kitchen and the roof, none of which scale with an extra bedroom's worth of floor. The marginal value of additional space in the same house is typically a fraction of the average price per square foot, and it falls as houses get larger.
Date of sale
If prices have moved since the comparable sold, adjust for time or your whole report is anchored to a market that no longer exists. This is the adjustment agents skip most often and regret most sharply in a market that turned mid-year. Derive it from your own market's movement over the period, not a national headline.
Bathrooms, and bedrooms only sometimes
A full bath is a real, quantifiable difference nearly everywhere. Bedroom count is trickier: a fourth bedroom carved out of the same floor area is worth much less than a fourth bedroom in a larger house, and adjusting for both bedroom count and living area double-counts the same square footage.
Condition and finish
The hardest to size and the one that most often explains a stubborn outlier. A comparable that sold after a full renovation is not the same property as the subject with an original kitchen, whatever the beds and baths say. Be specific about what you are pricing — kitchen, baths, roof, systems, windows — rather than applying one vague "condition" figure, which a seller will read as a number you invented.
Lot size, garage, and site
Lot matters where land is scarce and barely at all where it is not; the same extra quarter-acre can be worth a great deal in one town and nothing three counties over. Garage spaces are usually quantifiable. Negative site factors — a busy road, power lines, a commercial backing — tend to be larger than agents expect, and are best evidenced by finding a sale that suffered from the same thing.
Adjustments that are usually noise
- Cosmetic finishes — paint colour, carpet, light fittings. Priced into condition, not separately.
- Days on market. A slow sale is evidence about pricing, not a characteristic of the house. Note it; do not adjust for it.
- Seller concessions you cannot verify. If you can confirm them, adjust; if you are guessing, say so in the notes instead.
- Anything under about 1% of the sale price. It will not survive contact with a seller's scepticism, and a page of trivial adjustments makes the large ones look equally arbitrary.
Two sanity checks before you send it
Net and gross. If a comparable needs adjustments totalling a quarter of its sale price to resemble the subject, it is not comparable. Find a better one. Large gross adjustments are the clearest signal that the selection went wrong earlier.
Spread. Adjustments should tighten your adjusted prices, not scatter them. If four sales that ranged over $60,000 still range over $60,000 after all your work, the adjustments are not describing anything real — and it is better to notice that yourself than to have the seller notice it for you.
Doing this consistently
The failure mode is not ignorance, it is inconsistency: an agent who adjusts $15,000 for a bathroom on Tuesday and $8,000 on Thursday cannot defend either number. CompAgent proposes each adjustment with its arithmetic in view and applies the same logic to every comparable, so the figures are consistent across a report and across every report you produce — and you can override any of them where you know something the data does not.
The method around them is in how to build a CMA, and the distinction sellers most often confuse is in CMA vs appraisal vs online estimate.