How to arrange an automatic decrease in annual income
Suppose you've been in the habit of paying balance owed on credit card bills in full, monthly.
Suppose you take a friend to a restaurant (if non-deductible), go on vacation, or use it to pay for some other consumer item (i.e. something that you buy now and it's value is fully used up right away).
Being a bit short of money, you don't pay off the full amount owing, this month - and let that balance carry over the end of the year.
What you've done is spent more than you've earned, this year.
You'll have to pay it off next year. So that will leave you with less effective after-tax income, next year.
Not only that - you'll have to pay interest on the debt, until it's paid off.
Resulting in an additional reduction in your income, next year.
So - instead of enjoying a raise, next year - you've arranged an actual reduction in next year's effective income, income available to spend.
If you use it to buy a car, home or dining room table (capital goods that will provide a benefit to you over an increasing number of years, i.e., car lasts fewer years than home or table, loses value faster), the illustration doesn't apply, as you'll enjoy a benefit from your purchase in later years.
You might have been able to arrange a loan at more advantageous terms than using credit card, however.
I hope that you enjoy a raise next year, not a reduction in effective income,