Otd Calculator

---
name: otd-calculator
description: Use to compute out-the-door (OTD) cost from sale price + state + fees, or reverse-engineer a sales price ceiling from a target OTD. Handles trade-in tax credit if state grants it. Triggers include "compute OTD", "OTD math", "what's my OTD", "reverse OTD to sale price", "算 OTD", "算总价", Spanish phrases "calcula el precio final del carro", "calcula el precio total con impuestos y cargos", and any sale-price-vs-OTD disambiguation question.
---

# OTD Calculator

> **Caveat**: this skill is one author's playbook + 5-scenario stress test. Verify state fees / CPO terms / EV credits / dealer practices against current sources before quoting numbers to a dealer or making financial decisions. Not tax, legal, or financial advice.
> last_verified: 2026-05-18
> Scope: narrow OTD math only. For full negotiation flow see `../orchestrator/SKILL.md`. For state fee data see `../state-fee-lookup/SKILL.md`.

## Core formula (forward: Sale -> OTD)

```
Taxable = Sale + Doc  (in most states; CA is a notable exception, see gotchas)
Tax     = Taxable * (StateRate + LocalRate)
OTD     = Sale + Doc + Tax + Title + Reg + Other
```

`Other` covers tire/battery/environmental fees, EV reg surcharge, lien recording, and any add-ons that survived F&I. Should be a short itemized list, not a black box.

## Reverse formula (target OTD -> Sale ceiling)

Given a target OTD you will pay, solve for the maximum Sale price you can accept:

```
Sale = (TargetOTD - Doc * (1 + Rate) - Title - Reg - Other) / (1 + Rate)
```

Where `Rate = StateRate + LocalRate`. Doc is taxed in most states, hence the `(1 + Rate)` factor on Doc inside the bracket. Verify per-state in the state-fee-lookup skill.

## Trade-in case

In states granting trade-in tax credit (most; CA, KY, DC do NOT), trade value reduces the taxable base:

```
Taxable = (Sale + Doc - Trade)
```

Forward with trade:
```
OTD = Sale + Doc + (Sale + Doc - Trade) * Rate + Title + Reg + Other
```

Reverse with trade (solve for Sale given target OTD):
```
Sale = (TargetOTD + Trade*Rate - Doc*(1+Rate) - Title - Reg - Other) / (1+Rate)
```

If state does NOT grant credit, drop the `Trade` term from the taxable base.

## State quick rates (15 most-common)

| State | Combined typical | Doc cap | Title | Reg (1yr) | Trade credit |
|-------|------------------|---------|-------|-----------|--------------|
| NJ | 6.625% | $799 | $85 | $70 | Yes |
| NY | 8.875% (NYC) / 8% (most) | $175 | $50 | $100 | Yes |
| PA | 6% (8% Philly, 7% Allegheny) | none | $58 | $45 | Yes |
| CT | 6.35% (7.75% >$50k) | none | $25 | $80 | Yes |
| MA | 6.25% | none | $75 | $60 | Yes |
| CA | 8.75-9.5% (combined) | $85 | $25 | ~1%/yr MSRP | NO |
| TX | 6.25% (no local) | $225 | $33 | $50 + $200 EV | Yes |
| FL | 6-7.5% (combined) | none | $77 | $225 | Yes |
| IL | 7.5-10.25% (combined) | $347 | $155 | $151 | Yes |
| OH | 6-7.5% (combined) | $250 | $15 | $31 | Yes |
| MI | 6% | $230 | $15 | $100 | Yes capped 9k (2025) |
| GA | 6.6% TAVT one-time | none | $18 | $20 | Yes (on TAVT) |
| WA | 8-10% (combined) | $200 | $15 | $80 | Yes |
| MD | 6% | $800 | $100 | $135 | Yes |
| VA | 4.15% min $75 | $599 | $15 | $41 | NO |

Full 50-state + DC data: `../orchestrator/references/state_fees.md`.

## Worked examples

### Example 1: NJ example county, cash buyer, no trade

Sale $25,000, Doc $499, NJ 6.625%, Title $85, Reg $70.

```
Taxable = 25000 + 499 = 25499
Tax     = 25499 * 0.06625 = 1689.31
OTD     = 25000 + 499 + 1689.31 + 85 + 70 = 27343.31
```

### Example 2: CA Alameda 94703, trade-in, financed

Sale $28,000, Trade $8,000, Doc $85 (CA cap), CA combined 9.25% (Bay Area). CA does NOT grant trade credit.

```
Taxable = 28000 + 85 = 28085  (trade IGNORED - CA rule)
Tax     = 28085 * 0.0925 = 2597.86
Title   = 25
Reg     = ~280 (~1% of MSRP first year)
OTD     = 28000 + 85 + 2597.86 + 25 + 280 = 30987.86
```

Trade still reduces cash-out-of-pocket by $8,000 but not the tax bill.

### Example 3: TX Austin 78704, EV, no trade

Sale $32,000, Doc $150 (TX cap), TX 6.25% (no local), Title $33, Reg $50, EV surcharge $200/yr.

```
Taxable = 32000 + 150 = 32150
Tax     = 32150 * 0.0625 = 2009.38
Other   = 200 (EV reg premium)
OTD     = 32000 + 150 + 2009.38 + 33 + 50 + 200 = 34442.38
```

## Common gotchas

- **Doc-fee taxability**: most states tax Doc. CA explicitly does not. Florida varies by dealer. When in doubt assume taxed (conservative for buyer in reverse math).
- **Local rate stacking**: about 35 states have local tax. Use the buyer's residence ZIP, not dealer ZIP - the state collects tax based on registration address.
- **EV registration premium**: TX +$200/yr, IL +$100/yr, OH +$200/yr, WA +$225/yr. Adds to `Other`.
- **CA trade-in**: never reduces tax. KY and DC same. All others usually do.
- **GA TAVT**: 6.6% one-time title ad valorem tax in lieu of sales+ad valorem. Trade reduces TAVT base.
- **NC HUT**: 3% Highway Use Tax in lieu of sales tax; doc capped at $129.
- **NH/OR/MT/DE no sales tax**: any sales-tax line on a quote to these buyers is a template leak - demand re-quote.
- **MD doc cap**: $800 effective July 1 2024 (cap history $200 -> $300 -> $500 -> $800; older references citing $300/$499/$500 will mislead). MD's $800 cap is now HIGHER than VA's $599 - MD is no longer a low-doc state.

## Python helper

Use the existing script for forward or reverse math across all 50 states + DC:

```bash
# Forward: Sale -> OTD
python ../orchestrator/scripts/otd_calculator.py \
    --sales 25000 --state NJ --doc 499 --forward

# Reverse: target OTD -> Sale ceiling
python ../orchestrator/scripts/otd_calculator.py \
    --target 27500 --state NJ --doc 499

# CA with local stacking
python ../orchestrator/scripts/otd_calculator.py \
    --sales 28000 --state CA --doc 85 --local 2

# List all 50 states + their default rates / doc caps
python ../orchestrator/scripts/otd_calculator.py --list-states
```

Flags: `--target` (reverse) OR `--sales --forward`; `--state` two-letter code; `--doc` doc fee; `--local` extra local percentage (e.g. `1` = 1% extra); `--title --reg --addons` overrides.

## Sale vs OTD disambiguation

If a dealer quote or buyer message is ambiguous (e.g. "out the door at $28,000"), default to OTD interpretation and confirm. The classic trap: dealer says "$27,500" meaning Sale, buyer hears OTD, $1,800 surprise at signing. Always pin OTD explicitly in writing before any deposit.

## Links

- Full state fee table + cross-state titling math: `../orchestrator/references/state_fees.md`
- State-by-state lookup skill (narrower scope, faster): `../state-fee-lookup/SKILL.md`
- Negotiation playbook (escalation ladder, ADM kills): `../orchestrator/references/negotiation_playbook.md`