Paul Monaghan, the MP for Caithness, Sutherland and Easter Ross, signed off 255.75 extra hours for his brother Mark, who he employs as his constituency communications manager.
The payments were revealed in an Independent Parliamentary Standards Authority (IPSA) document, which also showed that SNP MP Corri Wilson for Ayr, Carrick and Cumnock paid her son Kieran Donoghue 118 hours of overtime. Mr Donoghue has since left the role and been replaced by his sister Shannon.
The document, retrieved under Freedom of Information legislation, did not give salary details of the close relations employed by the MPs. There is no suggestion that the MPs have broken any parliamentary rules.
But assuming Mark Monaghan worked a 35-hour week, 255.75 extra hours would translate into seven weeks overtime.
Jobs like that done by Mark Monaghan normally attract a salary of around £30,000. With overtime paid at 1.5 times the normal hourly rate reports yesterday suggested the extra payments would be worth up to £6,000. A post like that filled by Mr Donoghue would normally carry a salary of around £24,000.
Taxpayer Scotland director Eben Wilson said: “This does sound very much like cavalier behaviour. There really is no excuse for MPs not being on top of their office overheads, especially if relatives are involved. Taxpayers expect full transparency with an equally thorough approach to being accountable for every penny of our money that’s spent.”
A SNP spokesman said: “MPs employ their staff in accordance with Parliamentary rules and have made overtime payments to employees for work outside contracted hours as most responsible employers do.”