I have to tighten my belt this month.这个月我不得不勒紧裤腰带过日子。

　　其实中文中也一直有这个说法，形容经济拮据，手头不宽裕，需要节衣缩食度日。
　　再如：
The harvest was bad last year, they all had to tighten their belts.
去年收成不好，他们都不得不节衣缩食。