Real estate underwriting software vs. the spreadsheet you already have

Where spreadsheet underwriting still wins

Be honest about this before shopping for software. A spreadsheet is free, infinitely customizable, and you know exactly what every cell does because you wrote it. If you underwrite one or two properties a month in a market you know cold, a good model is not the bottleneck, and no tool will beat it on flexibility. Custom capital stacks, partnership splits, and one-off seller-finance structures are all easier to express in a sheet than in someone else's product.

Where it breaks down

• Input cost per deal. Comps, rent estimate, taxes, insurance, owner record. Fifteen to forty minutes of typing before you learn whether the deal is worth the fifteen minutes.
• One strategy at a time. Most models answer "is this a rental?" A tired duplex might be a weak rental and a strong flip. If checking the second exit costs another tab and another twenty minutes, you stop checking.
• No ranking. Fifty leads produce fifty files, not a sorted queue. There is no score to triage on, so the deal you look at first is the one that emailed you most recently.
• Silent version drift. Fix a formula today and your past underwriting no longer matches the file that produced it.

Side by side

BRRRR underwriting: the number spreadsheets usually miss

A BRRRR is two deals stapled together. You buy and rehab on short-term money, then refinance into long-term debt at the after-repair value. The verdict does not hinge on cap rate; it hinges on how much cash is still trapped in the property after the refi closes, which is a function of ARV, refinance LTV, seasoning, and rate. Get the ARV 8% wrong and a deal that looked like an infinite return leaves $22k stranded.

Basis models the bridge-to-refi handoff explicitly and returns a verdict: Infinite return, Strong BRRRR, Workable BRRRR, or Weak BRRRR, with the cash-left-in figure behind it.

Fix and flip math: carrying cost is the killer

Flip models tend to be optimistic in the same two places: the resale price and the length of the hold. Points and interest on hard money, taxes, insurance, utilities, and two sets of closing costs quietly consume the margin while the rehab line item gets all the attention. Basis prices the loan terms and the hold period into the return and lands on Strong flip, Thin flip, or Weak flip, alongside the wholesale read (Strong spread, Thin spread, No spread) on the same property, from the same inputs.

How to evaluate any underwriting platform

Basis is not the only tool in this category, and the right answer depends on your volume and strategy mix. Run whatever you are considering, including this one, through the same checklist:

• Does it model all four exits (hold, flip, BRRRR, wholesale) from one set of inputs?
• Does it show a confidence level on its estimates, or just a single number?
• Can you override every assumption: price, rehab, rate, LTV, taxes, vacancy?
• Does it compute an offer ceiling (MAO) and not only a return?
• Does it carry the deal past underwriting into a pipeline you actually work?
• Is the monthly analysis allowance enough for the volume you screen?
• Does it tell you where its data came from so you can verify locally?

One more filter: how the tool talks about its own AI. Any model, ours included, is an opinion formed from imperfect data. Basis says so in the product, on every AI memo: AI opinion - verify locally before money moves. A platform that presents an estimate as certainty is telling you something about how it handles the estimates you cannot see.

Frequently asked questions

What is real estate underwriting software?

It is a tool that turns a property address into a financed, strategy-by-strategy return model: value and rent estimates, comps, expense assumptions, loan terms, and the resulting cash flow, ROI, and offer ceiling. The difference from a spreadsheet is that the inputs are sourced and refreshed for you instead of typed in by hand.

Is a spreadsheet still good enough for underwriting rentals?

For one deal a week, yes. A well-built model is accurate and free. It stops scaling when you are screening dozens of leads, when several people share the file, or when a formula edit in one tab quietly changes every past deal you underwrote.

How is BRRRR underwriting different from buy and hold?

BRRRR has two capital stacks, not one: acquisition and rehab on short-term money, then a refinance at the after-repair value. The number that decides the deal is cash left in after refi, which depends on ARV, refi LTV, seasoning, and rate. Most rental spreadsheets model the hold and skip the bridge-to-refi handoff entirely.

What should fix and flip math include beyond purchase and rehab?

Hard-money points and interest for the true hold period, insurance and utilities while vacant, taxes, closing costs on both ends, agent commissions, and a contingency on the rehab budget. Flips usually fail on carrying cost and resale price, not on the rehab estimate.

How much does real estate underwriting software cost?

Basis is free to start (6 analyzer runs per month), $49/mo for Solo and $99/mo for Pro. Pricing across the category is typically per seat or per analysis volume, so compare the monthly analysis allowance and not just the sticker price.