If you go into a tax deed auction without a maximum bid number, you're relying on emotion instead of math. That's how investors overpay, erase their margin, and turn what looked like a deal into an expensive lesson.
At Tax Deed Collective, we teach students to make their money when they buy, not when they hope. One of the simplest ways to do that is by calculating your Maximum Allowable Offer (MAO) before the auction starts.
This guide breaks the formula down line by line, shows you a practical example, and explains how to stay disciplined when bidding goes past your number.
The MAO Formula
MAO = (After Repair Value × 70%) – Repair Costs – Carrying Costs – Profit Margin
This formula gives you a maximum bid ceiling based on the property's likely resale value, expected costs, and your target profit.
In a tax deed context, MAO helps protect you from common auction mistakes like:
- Bidding based on excitement instead of numbers
- Underestimating repair costs
- Forgetting title-related expenses
- Ignoring back taxes, insurance, and holding time
- Paying so much that there is no room left for profit
Why MAO Matters at Tax Deed Auctions
Tax deed auctions move fast. In some counties, you only have seconds to decide whether you'll keep bidding. If you haven't done the math in advance, it's easy to:
- Chase a property because it "feels cheap"
- Justify one more bid to avoid missing out
- Forget about hidden costs unique to tax deed investing
- Win a property that is technically below market value but still a bad deal
A good investor doesn't ask, "How high can I go?"
A disciplined investor asks, "What is the highest number that still leaves me protected?"
That's what MAO is for.
Line-by-Line Breakdown of the MAO Formula
1) After Repair Value (ARV × 70%)
After Repair Value (ARV) is what the property could realistically sell for after it's cleaned up, repaired, and ready for the retail market.
The 70% rule is a common investor guideline designed to leave room for:
- Selling costs
- Closing costs
- Financing or holding costs
- Unexpected repairs
- Profit
It is not a law. It is a conservative starting point.
How to estimate ARV
Use recent comparable sales for similar properties in the same market:
- Similar square footage
- Similar bed/bath count
- Similar lot size
- Similar condition after repairs
- Recent sales, ideally within the last 3 to 6 months
If your comps are weak or the market is declining, be more conservative.
Quick example
If a property's realistic ARV is $180,000, then:
$180,000 × 70% = $126,000
That means your deal has $126,000 total room before subtracting repairs, carrying costs, and profit.
2) Repair Costs
Next, subtract the money required to make the property marketable.
This is where many new investors get into trouble. At tax deed auctions, you may have limited access to the interior, so your repair estimate needs a margin for uncertainty.
What to include in repair costs
- Roof repairs or replacement
- HVAC, plumbing, and electrical
- Flooring and paint
- Kitchen and bath updates
- Windows and doors
- Debris removal and cleanup
- Structural issues
- Permit costs
- Contingency for unknowns
Tax deed investor tip
If you cannot inspect the inside, assume there may be hidden damage. Build in a stronger contingency than you would for a standard MLS deal.
If estimated repairs are $35,000, subtract that next:
$126,000 – $35,000 = $91,000
3) Carrying Costs
This is the section investors often underestimate, especially in tax deed deals.
Carrying costs are the expenses you'll incur while you own the property before resale or refinance.
In tax deed investing, these costs can be very different from a traditional purchase. You need to account for the fact that title issues, legal processing, and delays can extend your timeline.
What to include in carrying costs for a tax deed property
Back taxes or municipal balances
Depending on the county and auction structure, there may still be balances, fees, or cleanup items to confirm.
Include:
- Outstanding taxes if applicable
- Nuisance liens
- Code enforcement fines
- Water or utility balances where they survive the sale
Quiet title legal fees
One of the most important tax deed-specific expenses.
If you plan to resell through conventional channels, a title issue can slow or block your exit. In many situations, investors pursue a quiet title action or another legal process to improve marketability.
Include:
- Attorney fees
- Filing fees
- Service/publication costs
- Administrative legal expenses
Insurance
Even vacant properties need coverage.
Include:
- Vacant dwelling insurance
- Hazard insurance
- Liability coverage if needed
Holding time
The longer you hold, the more the deal costs.
Include:
- Property taxes during ownership
- Utilities
- Lawn maintenance
- Board-up or security costs
- HOA dues if applicable
- Interest or cost of capital
- Ongoing maintenance while preparing for sale
A simple carrying cost estimate
Let's say you estimate:
- Quiet title and legal: $7,500
- Insurance: $1,500
- Taxes, utilities, maintenance, and hold costs: $6,000
- Miscellaneous title-related or municipal items: $3,000
Total carrying costs = $18,000
Now subtract that:
$91,000 – $18,000 = $73,000
4) Profit Margin
This is the amount you want left over for taking the risk.
A lot of investors make the mistake of treating profit like "whatever is left." That is backwards.
Your profit should be planned in advance because you're taking on:
- Auction risk
- Limited inspection access
- Title uncertainty
- Repair uncertainty
- Market risk
- Time risk
How to set a profit margin
Your target profit depends on the size of the deal, the market, and your strategy. But the key is simple:
Do not bid away your profit.
For this example, let's say your minimum required profit is $25,000.
Now subtract that:
$73,000 – $25,000 = $48,000
Worked Example: Calculating Your Maximum Bid
Let's put the whole formula together.
Property Example
- Estimated ARV: $180,000
- 70% of ARV: $126,000
- Repair costs: $35,000
- Carrying costs: $18,000
- Desired profit: $25,000
Formula
MAO = ($180,000 × 70%) – $35,000 – $18,000 – $25,000
Answer
MAO = $48,000
That means $48,000 is your maximum allowable bid.
Not your starting bid.
Not your emotional bid.
Not your "maybe I can make it work" bid.
Your maximum.
If the bidding goes to $49,000 or more, the deal no longer fits your criteria.
What Happens If Bidding Passes Your Number?
This is where discipline matters more than knowledge.
At auction, it is easy to tell yourself:
- "It's only a few thousand more."
- "I'll make it up on the resale."
- "I don't want to lose after doing all this research."
- "Maybe repairs won't be that bad."
That kind of thinking destroys margins.
Your rule should be simple
If bidding goes above your MAO, stop bidding.
No exceptions based on adrenaline.
Because once you exceed your number, one of these things usually happens:
- Your profit shrinks
- Your risk increases
- Your holding time becomes harder to absorb
- Small surprises turn into big losses
How to Hold Your Discipline at the Auction
Knowing your maximum bid is one thing. Sticking to it is another.
Here are practical ways to stay disciplined:
1) Write your MAO down before auction day
Do not calculate on the fly.
Have a clear number for each property:
- ARV
- Repair estimate
- Carrying cost estimate
- Profit target
- Final MAO
2) Use a hard cutoff
Decide in advance that you will not exceed your number by even $1.
This removes negotiation with yourself in the moment.
3) Bid as if hidden problems are likely
Tax deed properties can come with surprises. If anything, your number should already reflect uncertainty.
4) Remember there will always be another deal
One bad buy can set you back months. Missing one property is far less expensive than overpaying for the wrong one.
5) Protect your capital first
The goal is not to win auctions. The goal is to win profitable deals.
Common MAO Mistakes to Avoid
Even with a formula, investors can still make errors. Watch out for these:
- Using inflated ARV comps
- Underestimating repairs because the property "looks okay" from the street
- Forgetting legal/title cleanup costs
- Ignoring back taxes, liens, or municipal balances
- Using unrealistic holding timelines
- Setting profit too low just to make the deal work
- Changing your MAO once the bidding gets competitive
If you have to force the numbers, it is probably not a deal.
A Better Way to Approach Tax Deed Auctions
At Tax Deed Collective, we teach students to evaluate deals before they ever bid. That means understanding not just the auction process, but the full investment picture:
- What the property is really worth
- What it will really cost
- How long it may really take
- What profit margin makes the risk worthwhile
That's how serious investors avoid becoming part of the crowd that learns through expensive mistakes.
Final Takeaway
Your maximum bid should be based on math, not momentum.
Use this formula before every auction:
MAO = (After Repair Value × 70%) – Repair Costs – Carrying Costs – Profit Margin
Then follow it with discipline.
Because in tax deed investing, the investors who last are not the ones who win the most bids.
They are the ones who refuse to overpay.
Want Help Analyzing Deals Before You Bid?
If you want a proven system for evaluating tax deed properties, estimating costs, and avoiding the mistakes that wipe out beginners, Tax Deed Collective can help.
We show investors how to:
- Research properties more confidently
- Estimate deal risk more accurately
- Analyze auctions across 3,500+ counties
- Build a repeatable bidding strategy based on real numbers
The right formula is powerful.
The right training makes it usable.