Newcastle Crown Court heard between June 1 and September 2 she transferred £21,286 to her bank, in 31 fraudulent transactions.
Prosecutor Matthew Hopkins told the court when discrepancies were spotted Wallace claimed there had been innocent mistakes and made a series of excuses in a bid to cover her tracks.
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Wallace, 31, of Aintree Road, Sunderland, who has never been in trouble before, admitted theft.
The court heard the cost of her offending to the family run firm has been a "lot more than money".
A spokesman who read out an impact statement on behalf of the business, which was established in 1981, said Wallace's dishonesty was "planned and very complex" and added: "She was taking money in the full knowledge of the stress people were under."
The court heard one worker was made redundant, a senior staff member was hospitalised due to stress and the company's charitable donations had to be halted because of what happened.
The spokesman added: "I cannot stress enough the extent the fraudulent, deceitful actions have had on our business and families."
Jennifer Coxon, defending, said Wallace had not realised how much money she had put into her own account and there was no suggestion she bought luxury goods.
Miss Coxon produced Wallace's bank statements to the court and said: "Just Eat, takeaways, that's essentially what she has wasted her money on.
"There was a trip to a caravan at Haggerston Castle, there was no large purchases such as a new car."
Miss Coxon said Wallace is "devastated" by the affect her offending had on the company and will have on her own family.
She added: "Her good character has gone now, in the most dishonest way."
Judge Sarah Mallett said Wallace splashed out on "extravagant living in everyday spending" and sentenced her to eight months behind bars.
The judge said the impact on the company went "far beyond a financial impact" and added: "This was a breach of a high degree of trust and responsibility.
"The offence is so serious only a custodial sentence can be justified."