Debt service is the hidden Kill Line driver

Jan 13, 2026

Households don’t fail because a debt balance looks scary on paper. They fail when payments stop fitting inside cash flow.

That’s why “debt service” (monthly payments) matters more than the raw balance.

Balance vs payment

  • Balance is a stock (how much you owe).
  • Payment is a flow (what you must pay every month).

Rates can make the payment bigger even if the balance doesn’t change:

  • variable-rate debt reprices (credit cards, some loans),
  • new borrowing gets expensive,
  • refinancing becomes harder.

The rate chain (why FEDFUNDS shows up everywhere)

The Federal Reserve’s policy rate influences:

  • short-term borrowing (credit cards, lines of credit),
  • mortgage rates (through bond yields and risk premiums),
  • business costs (which can affect hiring and wages).

So a “rates shock” can hit a household from multiple angles at once.

Practical warning signs

If you’re trying to stay above the line, watch for:

  • monthly payment creep (minimums rising),
  • shrinking surplus after essentials,
  • “temporary” borrowing becoming permanent,
  • delinquencies rising in the broader economy (stress spreading).

A safer way to think about debt

Instead of asking “How much do I owe?”, ask:

  1. “How many months could I pay everything if income dropped?”
  2. “Which payments can reprice upward quickly?”
  3. “Which costs are fixed and non-negotiable (housing, insurance)?”

These questions map directly to runway.

Disclaimer

This is educational content only and not financial, legal, medical, or investment advice.