Charlene and Martyn Riggon both pleaded guilty to defrauding HMRC of £122,000 and £90,000 each in income tax at a hearing at Birmingham Crown Court in May.
They ran Black Country Route Security in Willenhall, a company providing commercial security services to clients in the area.
On Wednesday, the court heard that the siblings had claimed VAT from customers that they failed to pay on to HMRC.
Customers cheques were cashed at Money Shops instead of being paid into the company’s bank account and the Riggons used two VAT numbers on invoices - an old one for the business before it was deregistered due to bankruptcy in 2006, and another which was “entirely fictitious”.
Prosecutor Matthew Brook QC said that between 2007 and 2018, Charlene Riggon, 38, of Gainsborough Crescent, Birmingham, who managed the office, cashed more than 1,000 cheques at Money Shop while her brother, 36, who managed security staff, cashed 45 cheques between 2007 and 2016.
Ms Riggon, a mother-of-three, did set up a self assessment for income tax in 2007 but submitted no returns between 2010 and 2017 while her brother, of Bloxwich Road, Walsall, was not registered for self assessment and paid no income tax from 2011 and 2017.
They both denied guilt when interviewed by the authorities in August 2017.
The Crown accepted that the offences did not lead to the pair “living the high life”, and recognising that they have no assets, made no attempt to recover money through a proceeds of crime application.
Mark Jackson QC, defending Charlene Riggon, said: “The profit was made by the business and that is the loss to HMRC.
“That was not money going into her pocket and spent by her.
“The overwhelming majority of it was supporting the business - we are looking at a business that was insolvent.”
The Riggons, who had both worked for the business since 2006, took over from their father, Clive, following his death in 2011.
His Honour Judge Martin Hurst said: “It is an unusual case made more difficult by the fact that you never kept any records.
“The Crown accepts that you were receiving no money at all from the business.
“You were on benefits and Charlene, you were working as a dinner lady and living in a council house.
“The mitigation is that the business was insolvent and you should have stopped trading when you took it over in 2011."
He sentenced both defendants to a 15 month jail sentence suspended for two years.
Ms Riggon was also sentenced to 25 days of rehabilitation with a community psychiatric nurse and they were both put under a three month curfew from 7pm to 7am and ordered to pay costs of £750.