tighten the purse strings

WordReference Random House Unabridged Dictionary of American English © 2025

purse′ strings′, 

1. the right or power to manage the disposition of money:
   in control of the family purse strings.
2. Idioms hold the purse strings, to have the power to determine how money shall be spent.
3. Idioms loosen or tighten the purse strings, to increase or decrease expenditures or the availability of money:
   The budget committee is in the process of tightening the purse strings.
• late Middle English 1375–1425