It might be thought that the audit of the PAYE system which has brought to light the overpayments and underpayments of tax under PAYE would bring in work for accountants and tax practitioners. This is not going to happen.
Overpayments of tax will be refunded by HMRC automatically. Those who have underpaid will fall into two categories. The first will be the people who knew their Codings were likely to be incorrect because they actually looked at them when the brown envelopes came through the post. Any anomalies will be because the benefit figures were wrong or the tax rates or allowances were wrong because there was a second job or a change in circumstances. It is likely that those who did not correct Codings which were wrong hoped that HMRC would not notice.
The second category will be those ostriches who never looked at their Codings. They will still not look; they will shrug their shoulders when they get notification of an underpayment.
Neither category of taxpayer will want to appoint an agent to manage the situation. It would be adding insult to injury to have to pay someone a fee when they already have to cough up some more tax. Anyway, in general it would not be worthwhile for agents to take anyone on as a client to look at their coding history. The fees which could be charged would not be sufficient to cover an agent's costs. Most of the people affected would not have a Universal Tax Reference (UTR) as they would not be filling in Tax Returns. That would mean that authorisation would have to be done with a paper application which would probably take three months for HMRC to process, by which time the Codings issue would be water under the bridge,
None of we agents' existing clients will have a problem. They will have had Tax Returns completed for them. Any overpayment or underpayment will have come out in the wash of Self Assessment.
So we can only look on, shake our heads, wonder at the noise and know that those who have underpaid probably knew there was an issue as they hid their heads in the sand.