How Much Contingency Should Your Rehab Budget Carry? A Risk-Scored Method That Beats a Flat 10%

Why a Flat 10% Contingency Is a Guess, Not a Plan

Contingency is money reserved for conditions you cannot see before you own the house. Think rotted subfloor under the vinyl, knob-and-tube wiring behind plaster, or a cracked cast iron drain under the slab. It is not a cushion for scope you already know about and forgot to price. If the kitchen needs cabinets and you left them off the budget, that is an estimating error, and it belongs in your line items, not your contingency.

A flat 10% treats every house the same, and houses are not the same. On a $25,000 cosmetic refresh of a 2005 build, 10% is $2,500, which you may never touch. On an $80,000 gut of a 1950s house with original plumbing and electrical, 10% is $8,000. A sewer lateral replacement and a panel upgrade can consume that before drywall goes up.

A better approach is to score the risk first and let the score set the percentage. Rate five factors from 0 to 2 points each, for a total between 0 and 10:

• House age: 0 for built after 1990, 1 for 1960 to 1990, 2 for pre-1960.
• System condition: 0 if updated, 1 if partially updated, 2 if original or unknown.
• Scope depth: 0 for cosmetic, 1 for kitchens, baths, and some systems, 2 for a full gut or structural work.
• Inspection access: 0 for a full inspection plus sewer scope, 1 for a walkthrough only, 2 for no access.
• Permit exposure: 0 for no permits, 1 for standard permits, 2 for major permits or unpermitted work to legalize.

Map the total to a band. A score of 0 to 3 carries 5% to 8%, a score of 4 to 6 carries 10% to 15%, and 7 to 10 carries 18% to 25%. Within a band, lean toward the high end when any single factor scores a 2. A house scoring 8 with a $60,000 rehab would carry 20%, or $12,000.

That number flows straight into your offer. With a $300,000 ARV, MAO equals $210,000 minus repairs, so a $72,000 all-in rehab supports a $138,000 offer. Underfund contingency and you overpay before the first wall comes down.

Worked Example 1: A Low-Risk Cosmetic Flip

Start with the kind of deal most new flippers should look for first. It's a 2002 three-bed, two-bath ranch where the seller replaced the HVAC, water heater, and roof within the last six years. Your walkthrough turns up dated finishes but nothing structural. The scope is interior paint, LVP flooring throughout, new light fixtures and plumbing trim, and a landscaping cleanup to fix the curb appeal.

Run it through the risk score and it lands at 2 points. You add one point because the house is over 20 years old, so original supply lines or a soft subfloor spot under old carpet could still surprise you. You add one more because flooring jobs routinely uncover leveling issues. Everything else scores zero. The mechanicals are documented, the scope is cosmetic, and no permits or structural work are involved. A score of 2 puts you in the 8% contingency tier.

Your line-item budget comes to $38,000. Apply 8% and the math looks like this:

• Contingency: $38,000 x 0.08 = $3,040
• Total rehab: $38,000 + $3,040 = $41,040
• MAO: ($280,000 x 0.70) - $41,040 = $196,000 - $41,040 = $154,960

Now compare that to padding with a flat 10%. Ten percent of $38,000 is $3,800, which pushes total rehab to $41,800 and drops your MAO to $154,200. That's about $760 less offer room on a house where the biggest realistic surprise is a few sheets of underlayment or a cracked toilet flange. The extra cushion buys almost no real protection, because the expensive failure points (roof, HVAC, electrical, foundation) have already been checked off.

That $760 matters more than it looks. In a competitive bid situation, a few hundred dollars can decide whether your offer gets accepted or the house goes to another investor who priced the risk more precisely. Scoring lets you stay disciplined on the risky deals and sharpen your pencil on the clean ones, which a blanket 10% will never do.

Worked Example 2: A 1950s House With Original Systems

Now take a 1954 ranch with an ARV of $310,000. It still has original galvanized supply lines, a 60-amp electrical panel, and a kitchen and bath that need a full gut. There's also no crawlspace access, so nobody has seen the subfloor, the drain lines, or the joists. Your contractor walks it and prices the base rehab at $62,000.

Run it through the risk score and it lands at 8 points:

• Original galvanized plumbing: 2 points
• 60-amp panel needing a service upgrade: 2 points
• Kitchen and bath gut (walls open, hidden conditions exposed): 2 points
• No crawlspace access (unverified structure and drains): 2 points

Eight points puts this house in the 20% tier. That means $62,000 x 0.20 = $12,400 in contingency, for a total rehab budget of $74,400. Your MAO becomes ($310,000 x 0.70) - $74,400 = $217,000 - $74,400 = $142,600. A buyer using a flat 10% would carry only $6,200 in contingency, budget $68,200, and offer up to $217,000 - $68,200 = $148,800.

That $6,200 gap looks like caution costing you the deal. Then demo starts, and the plumber scopes the main line. The original clay sewer lateral is cracked and root-packed, and replacement runs $15,000. The flat-10% buyer has $6,200 set aside, so they eat an $8,800 overrun straight out of profit.

The risk-scored buyer absorbs $12,400 of that bill from contingency, leaving a $2,600 gap. But they also paid $6,200 less for the house, so the lower offer covers that gap with $3,600 to spare. Same house, same surprise, and one investor is $8,800 in the hole while the other is still ahead. On a 1950s house with original systems, a sewer line is a predictable risk, and the score priced it in before you signed.

Edge Cases: Where Contingency Gets Tricky

Contingency covers surprises in the scope of work, not surprises in the calendar. If your plumber disappears and the project slips six weeks, that cost belongs in a separate holding-cost line. On a $250,000 hard money loan at 12%, interest alone runs $2,500 a month, so a six-week delay adds roughly $3,460 before you count utilities, insurance, and taxes. Mixing that into contingency means you burn your repair cushion on interest and have nothing left when the drywall comes down and reveals rot.

Financing creates the next trap. Most hard money lenders fund rehab through a draw schedule tied to a specific scope of work, and many exclude contingency from what they will reimburse. Draws also arrive after inspection, so you front the money first. If your rehab is $60,000 and you carry 15% contingency, plan on holding $9,000 in cash on top of your down payment, closing costs, and holding reserves. Ask your lender in writing whether overruns are fundable before you assume they are.

Your contingency doesn't have to be one flat percentage. You can score each line item on its own risk. Cosmetic finishes you can see and price rarely blow up, while anything underground or behind walls can double. Here is a blended example on a $60,000 budget:

• Paint, flooring, fixtures ($40,000 at 5%): $2,000
• Electrical panel and partial rewire ($8,000 at 15%): $1,200
• Sewer line repair ($12,000 at 25%): $3,000

The total is $6,200, about 10.3% overall. It's close to a flat 10%, but now the dollars sit where the risk actually lives.

The cheapest way to shrink contingency is to remove unknowns before closing. A sewer scope costs about $150 to $300, an electrical inspection by a licensed electrician runs a few hundred dollars, and with seller permission you can cut a small inspection hole in a suspect wall. Spending $500 during due diligence can move a sewer line from a 25% guess to a 5% known quote. That changes your offer math in your favor.

Contingency Mistakes That Quietly Kill Flip Profits

Most blown flip budgets don't come from one disaster. They come from small habits that drain the contingency before a real surprise ever shows up. The first habit is using contingency to hide unpriced scope. If you know the deck needs replacing but never got a number for it, that's not contingency. It's a missing line item, and it will eat the cushion meant for things you couldn't see.

The second mistake is spending contingency on upgrades mid-project. Quartz instead of laminate or a nicer tile because the house "deserves it" feels harmless when the budget still looks healthy. Then the crew pulls up the bathroom floor and finds a rotted subfloor, and the money is already gone. If an upgrade truly raises your ARV, give it its own line and rerun the deal math.

Third, investors often apply the percentage to the wrong base. Say a $40,000 rehab breaks down to $16,000 in materials and $24,000 in labor. A 15% contingency on materials only is $2,400, while 15% on the full budget is $6,000. That $3,600 gap matters because labor is where many overruns land, like an extra two days of a plumber chasing a hidden leak.

Fourth is cutting contingency to win a bidding war. Dropping it from $6,000 to $2,000 so you can offer $4,000 more doesn't reduce the house's risk at all. It just moves that risk straight onto your profit. The fifth mistake is never tracking actual overruns. After each flip, compare estimated versus actual cost per category. If electrical ran 30% over on your last three pre-1960 houses, your risk score for that category should reflect it.

This is where a line-item budget beats a gut feeling. When you paste an address into FlipSmrt, the rehab budget comes back broken out by category, so you can see which lines carry real unknowns. Interior paint and fixtures are predictable. The sewer lateral, electrical panel, and roof decking are not. Assign higher contingency to those specific lines, add them up, and your total is grounded in the actual scope instead of a round number.

Rehab Contingency FAQ

Should contingency be included in the MAO formula? Yes. Treat it as part of your repair costs, not as a separate cushion you hope you won't need. On a house with a $300,000 ARV, a $50,000 scope, and a 15% contingency, your repair figure is $57,500. That makes your MAO ($300,000 x 0.70) - $57,500 = $152,500, not the $160,000 you'd get by leaving contingency out. That $7,500 gap is exactly the money that disappears when you skip it.

What if I don't use it? Unspent contingency becomes profit, which is the best possible outcome. It is not a sign you overbudgeted or a reason to trim contingency on the next project. One clean rehab doesn't make the next house less risky. Score every property on its own age, systems, and scope, and let the number land where the risk puts it.

Do lenders count it? It depends on the lender, so ask before you close. Some hard money lenders want a contingency line in your scope of work and will fund it through draws like any other item. Others only fund itemized repairs, which means contingency comes out of your pocket. That changes your total cash invested, and with it your cash-on-cash return, so know which kind of lender you have.

How should contingency change for a BRRRR versus a flip? A BRRRR usually deserves the same or higher contingency, not less. You're often replacing systems for a long hold rather than patching for a quick sale. Every overrun also becomes cash trapped in the deal after the refinance. A flip has more timeline pressure, but a BRRRR overrun quietly drags down your return for years.

Is 25% ever too low? Yes, on structural or fire-damaged houses. When a foundation is moving or framing is charred, no percentage can stand in for an actual scope. Get a structural engineer's report first, price the repairs it specifies, and only then apply contingency to that real number. Until you have the engineering scope, you don't have a budget at all.