Command Line Interface (CLI)¶

The toolkit includes a powerful CLI for simulating amortization schedules, comparing refinance options, and visualizing scenarios. Install dependencies and run the CLI directly.

Getting Started¶

Once installed (see README), you can invoke the CLI:

python -m cli.cli [command] [options]

Or install a shortcut entry point:

pip install -e .
mortgage --help

Available Commands¶

Command	Purpose
`amortize`	Generate amortization schedule
`compare-apr`	Compute effective APR with points/fees
`breakeven`	Evaluate refinance breakeven month
`plot`	Compare multiple loan scenarios visually

Amortization Example¶

mortgage amortize \
  --type fixed \
  --balance 400000 \
  --rate 6.0 \
  --term 360

Generates a monthly amortization schedule and shows first 12 rows.

Recast and Refinance¶

Add optional flags to simulate real-world events:

mortgage amortize \
  --type fixed \
  --balance 400000 \
  --rate 6.0 \
  --term 360 \
  --extra-payment 300 \
  --recast-date 2027-01-01 \
  --lump-sum 10000 \
  --refinance-date 2029-07-01 \
  --new-rate 5.25 \
  --new-term 240

Effective APR Comparison¶

mortgage compare-apr \
  --principal 400000 \
  --rate 6.0 \
  --term 360 \
  --points 1.0 \
  --fees 2500

Returns the effective APR based on net loan proceeds and IRR.

Breakeven Analysis¶

mortgage breakeven \
  --monthly-savings 180 \
  --closing-costs 3500

Tells you how many months it takes for the refinance savings to break even.

Multi-Scenario Comparison¶

mortgage plot \
  --scenarios 400000 6.0 360 \
  --scenarios 400000 5.25 360

Visually compares principal and interest paths across loan structures.

Output Options¶

--output FILE.csv saves amortization to disk
--start-date YYYY-MM-DD controls loan origination date
--extra-frequency [monthly|biweekly] for recurring extra payments

📎 Next: Examples and Recipes