UC and personal pension payment

Nosama

I am self employed and have been for several years. March 2020 covid hit, I was ineligible for Seiss, it was necessary to claim UC. To calculate what UC I will receive my personel pension is taken into account based on a gross figure. 
At present have had intermittent work which makes my UC void, however this income goes on my self assessment paperwork. If I reach my tax threshold through worked income, my pension is also taken into account at a gross figure, I will need to pay tax on this aswell.
Conclusion UC less Pension Gross, then I will be taxed on my pension by the HRMC, is this the case or do I use payments taken by UC via my pension to reduce my UC allowance
from my income listed on my self assessment. Therefore am being hit twice by UC & HRMC
Hope you understand help or clarification would be appreciated 
Regards
Alan

NedS

UC works on net incomes - the money you have actually received after any tax has been deducted.

It is your responsibility to declare to UC what your pension income is. If your pension income changes, for example it goes up due to an annual increase, or it decreases as tax is now being deducted, you will have to notify UC. Assuming it's the same every month, you only need to declare it once, and then again if it changes. You will see it appear on your UC statement as a deduction for other income. So you won't be penalised twice - if you have received less pension because some tax has been deducted at source, then you will get more UC because less pension received will be deduced from your UC payment.

Universal Credit do receive notification of pension payments from HMRC so they can verify what you have told them, but they are not automatically processed, hence you must declare it manually. Note that you must also declare any tax rebates you have received with would also be treated as income.

Nosama

I appreciate that my pension is taken off any UC entitlement. 
Example
Pension £400 gross
Pension £300 net taxed at source
UC £800
At present £800- £400 = £400 UC 
Pension taxed at source I would receive an additional £100 UC as I was only receiving £300 from my pension
As I do not pay tax at source they use the gross amount of my pension , but as I am self employed, if I earn over the tax threshold then I will be taxed on that amount above the tax threshold.
Example
Self Employment £12500 + pension £4800 = £17,300 total I would be taxed on the £4800.
So if I claim UC for say 7 months and if I pay tax on the pension through my tax returns surely I would be owed £700 either by being underpaid by UC because the tax I have paid to hrmc or £700 overpaid in tax to the hrmc.
Regards for any further help, bit long winded but trying to understand the issue

calcotti

As a self employed person you report income and expenditure each month on a cash basis. When you pay your tax bill that will be an expense which will reduce the 'earnings' figure in that month resulting in higher UC for that period.