One GP dismissed the idea as 'stupid' because surgeries were likely to be empty.
Boxing Day falls on a Saturday this year and is not a bank holiday, prompting some PCTs to call for surgeries to provide extended hours as usual.
Milton Keynes PCT expects practices to open. A spokesman said: 'Practices offering extended hours on a Saturday will be open on 26 December.
'Practices should be open at exactly the same times as their normal hours including extended hours, and be fully functioning as normal.'
However GP contacted practices in the area and most said they would close on Boxing Day despite the ruling.
Dr Paul Roblin, chairman of the Buckinghamshire, Berkshire and Oxon LMC, criticised an edict from West Berkshire PCT asking surgeries to make up the time during the following weeks.
He pointed out that extended hours are meant to boost access for people who work, but since they are on holiday, Boxing Day opening was unnecessary.
Dr Roblin said: 'It's nonsensical. Extended hours are not about emergency care, so there is no benefit. Some of the PCTs are behaving very stupidly.'
A spokesperson for NHS Berkshire West said: 'The PCT is happy for (practices) to take a flexible approach to providing extended hours over the holiday period provided they reschedule at an alternative time and that the change is communicated to patients.'
Kingston PCT in Surrey is asking surgeries to make up the time during the following week and PCTs in Birmingham East and North asked surgeries to make up the time before the end of January. A DoH spokesman said the Saturday arrangements are at PCTs' discretion.