Verbs ending in a consonant followed by -y change the -y to -ied in the past tense form.
Economy is regular. It follows the -ied Conversion rule.
Use past time markers: "Yesterday, she economied to the store."
No. Use "did not economy" (not "did not economied").
The verb economy follows the standard English past tense conjugation rule. When forming the past tense, economy becomes economied. This follows the -ied Conversion pattern, which is one of the most common conjugation rules in English.
Understanding why economy becomes economied helps with spelling and pronunciation. Verbs ending in a consonant followed by -y change the -y to -ied in the past tense form.
When using economied in writing, remember that it functions as a past tense verb and typically appears with time markers like yesterday, last week, or ago. For example: "Yesterday, she economied to the store." The past tense form does not change based on the subject — I economied, you economied, he/she economied, we economied, they economied.