Income tax on company pensions when you have 2 separate pensions from different employers

If you receive 2 company pensions from 2 different providers, how does each provider know how much income tax to deduct, as one pension on its own might be below the personal allowance but when combined the personal allowance is exceeded. In addition, what then happens when you also start receiving the state pension ( on top of the two company pensions)too in terms of income tax?

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Hi david.bremner Bremner,
Both pension providers will contact us when you start receiving your pension income from them,
We will update your tax record with both providers, calculate a tax code for each pension based on the allowances available and income projected. We will send notice of these codes to your pension providers.
When you begin receiving State Pension, your tax free allowances will be reduced to account for the tax you would owe on that State Pension.
We will then recalculate your tax codes, and send notice of these updated codes to all of the pension and employment sources affected. 
Thank you. 

I have a related problem. I have just started receiving my employment pension, which is now my main source of income. I have been using a smaller, flexi-access drawdown pension but intend to stop drawing on this later this year. HMRC has allocated a much larger tax code to the smaller pension (meaning I won't pay any tax on this) and a smaller tax code to my main income. It would make much more sense for this to be reversed, so that my tax allowance is allocated to my main pension, which I will draw for the rest of my life. Can the way the tax codes/allowances are allocated to the two pensions be changed?

Hi,

To review the tax codes you will need to contact HMRC at:

Income Tax: general enquiries

Thank you.